STARFISH AS FEEDINGREDIENT FOR PIGLETS
SØSTJERNER SOM FODERMIDDEL TIL SMÅGRISE
PIA SØRENSEN
STUDENT ID: 20107218
MASTER THESIS · AGROBIOLOGY · AUGUST 2015
Supervisor:
Jan Værum Nørgaard, Department of Animal Science, Aarhus University
PREFACE
This current thesis is completed as the final part of the master degree in Agrobiology with area of
specialisation in animal health and welfare, at Science and Technology, Aarhus University. The
thesis corresponds to 45 ECTS and includes a review of published literature and a practical
experiment. It was a privilege, within the scope of the budget and what was realistic in relation to
the objective of the study, to be the one who should design the study appropriate. The experimental
work was carried out during November and December 2014 at the facilities of Aarhus University,
Research Centre Foulum. The practical experiment and results are presented in a manuscript, and
are intended to be submitted to the Animal Feed Science and Technology. As the manuscript only
presents some results and a discussion of the corresponding results, a separate section will present
additional results and discus the results in general.
The project was financed by the Green Development and Demonstration Programme under the
Ministry of Food, Agriculture and Fisheries, Denmark, in cooperation with the Danish Shellfish
Centre, Foreningen Muslingeerhvervet and Agro Korn.
This thesis aims to clarify perspectives for feeding newly weaned pigs with a new alternative source
of animal protein. The target audience of this master thesis includes students, pig farmers, advisors
and scientists within the field of pig nutrition with special interest in feeding of newly weaned pigs.
I would like to express my gratitude to my supervisor associate professor Jan Værum Nørgaard,
Department of Animal Science – Animal Nutrition and Environmental Impact, Aarhus University,
for support, useful discussions and feedback through all parts of the process.
Also a great thanks to the personnel at the pig facilities at Research Centre Foulum, Aarhus
University, for helping with collection of data during the practical experiments.
Foulum, August 2015
Pia Sørensen
I
II
SUMMARY
Starfish in high concentrations are considered pests by the commercial mussel fishermen in
Denmark because starfish are predators to mussels that are otherwise used for human consumption.
A regulation of the population size is therefore needed. Concurrently, the organic feeding business
wants new protein sources, which can contribute in supplying the livestock production with
essential amino acids. The need for such protein sources is reinforced in a time, where feed for
organic animals are determined to be of 100% percent organic origin in a foreseeable future.
Starfish meal is not a new product, and was evaluated as feed ingredient in studies with poultry
several decades ago. It was concluded that the protein fraction in starfish meal (SM) was
comparable to fish meal (FM) in quality. The objective of the present study was to investigate
whether piglets fed a diet containing SM as a high-quality protein source would perform on equal
terms with pigs fed traditional diets for piglets weighing 9 to 15 kg of bodyweight (BW).
The effects of including SM as an alternative protein source in diets for piglets on performance,
faeces characteristics and plasma parameters were investigated. Four diets were formulated to
contain different protein sources; FM, soy protein concentrate (SPC) and two levels of SM (SM5%
and SM10%). All diets contained 174.4 g soybean meal (SBM)/kg and were supplemented up to
166-172 g SID CP/kg with either FM, SPC, SM or a combination giving raise to two SM + SPC
diets with different levels of SM and SPC. One week after weaning, 96 pigs (BW 9.6 ± 0.4 kg) were
individually housed and allocated to one of the four diets (n=24) and feed ad libitum for a 14-d
period. Average daily feed intake (ADFI), average daily gain (ADG) and gain to feed ratio (G:F)
were determined. Pigs fed the SM10% diet had an ADG 23-28% lower (P<0.001) than pigs fed the
other diets, despite that they ate the same amount of feed. Faeces characteristics were evaluated by
visual judgement during five days and no differences were observed, indicating no effect of the diet
on diarrhoea. Blood samples were collected on d 15. Plasma Ca concentration was higher (P<0.001)
in pigs receiving SM10% compared to FM, SPC and SM5%. The opposite was the case with P
where the concentration was lower (P<0.001) in SM10% compared to FM, SPC and SM5%.
In conclusion, feeding diet SM5% resulted in performance equal to pigs fed the control diets. The
negative effect on performance when feeding the SM10% diet, may be the high Ca level and wide
Ca:P that affects digestibility and absorption of P negatively. Moreover, formation of mineralphytate complexes, may reduce mineral bioavailability. The determining factor for the maximum
inclusion level of SM in diets for piglets may be the dietary Ca level and the resulting Ca:P.
III
SAMMENDRAG (DANISH SUMMARY)
Muslingefiskeriet i Danmark er plaget af enorme mængder søstjerner, som æder muslingerne på
havbunden, der ellers fiskes og bruges til human konsum. En regulering af søstjernebestanden er
derfor ønsket. Samtidig, efterspørger den økologiske foderstofbranche nye proteinkilder, der kan
bridrage med essentielle aminosyrer til husdyrproduktionen. Behovet for sådanne proteinkilder er
forstærket i en tid, hvor foder til økologiske dyr indenfor en årrække skal være af 100% økologisk
oprindelse. Søstjernemel (SM) anses ikke for værende et nyt produkt, da det for flere årtier siden
blev evalueret som foderingrediens i studier med fjerkræ. Det blev konkluderet, at kvaliteten af
proteinet i SM var sammenlignelig med den i fiskemel (FM). Formålet med studiet var, at
undersøge om smågrise fodret med en blanding indeholdende SM som høj-kvalitets proteinkilde, vil
udvise samme produktivitet som hos smågrise fodret med traditionelle blandinger til smågrise i
vægtintervallet 9-15 kg.
Effekten af at inkludere SM i foderblandinger til smågrise blev bestemt ud fra produktivitet, fæces
karakteristik og plasma parametre. Fire blandinger blev sammensat til at indeholde forskellige
proteinkilder; FM, sojaprotein koncentrat (SPK) og to niveauer af SM, henholdsvis 5 og 10%. Alle
blandinger indeholdt 174,4 g sojaskråfoder/kg, og FM, SPK eller SM, eller en kombination af SM
og SPK i forskellige mængder, resulterende i 166-172 g standardiseret ileal fordøjeligt råprotein/kg
foder. En uge efter fravænning, blev 96 smågrise (9,6 ± 0,4 kg) individuelt opstaldet og tildelt en af
de fire blandinger (n=24) og fodret ad libitum i 14 dage. Gennemsnitlig daglig foderindtag og
tilvækst, og tilvækst til foder ratio blev bestemt. Tilvæksten ved tildeling af foder med 10% SM var
23-28% lavere (P<0,001) end hos grise tildelt de andre blandinger, trods samme foderoptag. Fæces
karakteristik blev evalueret vha. visuel vurdering henover 5 dage. Ingen forskel blev observeret,
betydende at blandingerne ingen effekt havde på forekomsten af diarré. Blodprøver blev taget på
dag 15. Calcium koncentrationen i plasma var højere (P<0,001) hos grise tildelt 10% SM
sammenlignet med de andre blandinger. Det modsatte var tilfældet med P, hvor plasmaindholdet
var lavere (P<0,001) hos grise tildelt 10% SM sammenlignet med de andre blandinger.
En blanding med 5% SM giver en produktivitet som hos smågrise tildelt kontrolblandingerne. Den
negative effekt af 10 % SM på produktivitet kan være det høje Ca indhold og brede Ca:P, der
påvirker fordøjelse og absorption af P negativt, sammen med reduceret mineraltilgængelighed
grundet dannelse af mineral-fytate komplekser. Den bestemmende faktor for maksimum iblanding
af SM i blandinger til smågrise er indholdet af Ca i foderet og den resulterende Ca:P.
IV
TABLE OF CONTENTS
PREFACE .............................................................................................................................................I
SUMMARY ....................................................................................................................................... III
SAMMENDRAG (DANISH SUMMARY) ...................................................................................... IV
ABBREVATION KEY .................................................................................................................... VII
INTRODUCTION ............................................................................................................................... 1
Hypothesis and objective.................................................................................................................. 2
LITTERATURE REVIEW .................................................................................................................. 3
1
2
3
4
5
The need for alternative protein sources ....................................................................................... 3
1.1
Constraints in protein sources ............................................................................................... 3
1.2
Demands in relation to feeding organic pigs ......................................................................... 3
1.3
Environmental benefit ........................................................................................................... 6
Starfish .......................................................................................................................................... 8
2.1
Occurrence............................................................................................................................. 8
2.2
Handling and use of starfish .................................................................................................. 9
2.3
Chemical composition of starfish ........................................................................................ 10
2.4
Starfish as feed ingredient ................................................................................................... 13
Nutrient requirement of piglets ................................................................................................... 16
3.1
Energy requirement ............................................................................................................. 16
3.2
Protein and amino acids requirement .................................................................................. 17
3.3
Mineral requirement ............................................................................................................ 18
Practical feeding around weaning ............................................................................................... 19
4.1
The transition of weaning .................................................................................................... 19
4.2
Diet characteristic and protein sources ................................................................................ 19
Final remarks and conclusion of literature review ..................................................................... 23
GENERAL DISCUSSION OF RESULTS AND THE STUDY ....................................................... 53
6
Discussion and future development ............................................................................................ 53
6.1
Design of the study .............................................................................................................. 53
6.2
Faeces score method ............................................................................................................ 54
6.3
Results from the study ......................................................................................................... 55
6.4
Possibly same features in starfish meal and fish meal ........................................................ 56
6.5
Possibility of further development of the product ............................................................... 58
V
CONCLUSION .................................................................................................................................. 59
IMPLICATATIONS AND PERSPECTIVES ................................................................................... 60
LITERATURE CITED ...................................................................................................................... 61
VI
ABBREVATION KEY
AA
Amino acids
ADFI
Average daily feed intake
ADG
Average daily gain
ANF
Anti-nutritional factors
BW
Body weight
Ca
Calcium
CP
Crude protein
CAA
Crystalline amino acids
DHA
Docosahexaenoic acid
EPA
Eicosapentaenoic acid
FA
Fatty acids
FCR
Fed conversion ratio
G:F
Gain to feed ratio
ME
Metabolisable energy
N
Nitrogen
NE
Net energy
P
Phosphorus
PSP
Paralytic shellfish poison
PUFA
Polyunsaturated fatty acids
SBM
Soybean meal
SID
Standardized ileal digestibility
SPC
Soy protein concentrate
VFI
Voluntary feed intake
VII
VIII
Introduction
INTRODUCTION
Mussel fishermen in Limfjorden, Lillebælt and Isefjorden in Denmark, have reported that the
occurrence of starfish in the inner Danish waters have been increasing the past years, and the
mussel fishery has been plagued by substantial amounts of starfish that negatively affect the fishery
of mussels (Kjølhede, personal communication, 2015). Likewise, the Danish Shellfish Centre has
documented that mussels in many relaying areas have been eaten by starfish and confirms that the
density of starfish in areas of Limfjorden is increasing (Nielsen et al., 2014). Therefore, there is a
need to regulate the population of starfish. Concurrently, the organic feeding business needs new
protein sources, which can contribute in supplying the livestock production with indispensable
amino acids (AA). Because starfish has been proven to have a potential AA and protein profile,
which can lead to a reduction in nitrogen excretion and emission, it will help making organic
production more sustainable. The need for such protein sources is reinforced in a time, where feed
for organic animals are determined to be of 100% percent organic origin by December 31 2017
(Smith et al., 2014).
In 2014 the project “Starfish as New Source to Marine Proteins” (STARPRO) was financed by the
Green Development and Demonstration Programme under the Ministry of Food, Agriculture and
Fisheries, Denmark, a project cooperation between the Danish Shellfish Centre, Foreningen
Muslingeerhvervet, Agro Korn, and Aarhus University, Foulum. The purpose of STARPRO is to
establish a sustainable fishery for starfish in preparation for producing a 100% organic feed
ingredient for monogastric livestock. The project includes the whole value chain with the concrete
goal to develop cost-effective methods for production of starfish meal (SM) and within a
foreseeable future establish a fishery of 10,000 t of starfish a year amounting a production of 2,500 t
of SM a year. The activities in the project STARPRO will constitute determination of the
population size, testing of developed methods for production of SM constituting the preparatory
processing e.g. washing sand of the caught starfish to grinding of the dried starfish, designing of
diets containing SM and test the diets including SM in feeding studies with poultry and pigs. It is
expected that it will generate employment through the establishment of a Danish production of feed
for monogastric livestock containing SM. The environment will also benefit from the removal of
starfish, since the fishery of starfish will remove nutrients from the coastal waters, and the emission
of nutrients from organic farming will be less due to improved feed efficiency. Furthermore, the
production of mussels for human consumption will be more profitable as the result of reduced
predation on mussels. On the basis of existing analysis of SM on the chemical characteristics and
1
Introduction
the results of ileal digestibility in pigs (Nørgaard et al., 2015), it is assessed that the product is
suitable as feed ingredient for piglets, by which the possibility of SM as feed ingredient for piglets
were requested to be examined.
Hypothesis and objective
The hypothesis of the thesis:
It is hypothesised, that SM as a high-quality protein source can be used as feed ingredient for
piglets.
The objective of the thesis:
The objective of this master thesis was to describe the need to investigate new protein sources for
piglets due to the increasing need for alternative protein sources, together with requested
sustainability and local origin of feed ingredients. Moreover, the increasing problems experienced
with starfish in the Danish waters leads to description of the occurrence of starfish and the possible
use as feed ingredient for piglets. The objective was, furthermore, to describe the piglets need for
nutrients post-weaning and the high-quality protein sources used at the present. Finally, a study was
conducted using four diet of which two contained SM adjusted for piglets with body weight 9 to 15
kg. In the study it was investigated, whether the use of SM as feed ingredient in diets for piglets will
give the same average daily feed intake (ADFI), average daily gain (ADG) and gain to feed ratio
(G:F) as traditional diets.
2
Literature review
LITTERATURE REVIEW
1
The need for alternative protein sources
1.1 Constraints in protein sources
Protein feedstuff used earlier, have either become a limited resource as fish for the production of
fish meal (FM), or banned in many countries as animal by-products like meat and bone meal on
account of the risk of transferring transmissible spongiform prion transferred diseases such as BSE.
Moreover, vegetable protein sources often used are to a great extend genetically modified. Sieradzki
et al. (2006) found that about 98% of the soybean samples collected contained transgenic soya, a
feed ingredient used for the production of both supplementary and compound feedstuffs. In many
countries there is still strong public opposition against using genetic modified plants and is
considered unsuitable as feed for food producing animals.
Despite the fact that soybean meal (SBM) is often genetically modified, SBM is the most important
protein source in pig feed, and is generally known as a protein source with a consistent and high
quality (Jezierny et al., 2010). It contains a comparable high portion of indispensable AA that are
easily digestible for monogastric animals. In temperate environments, soybeans can be difficult to
cultivate and the pig industry relies heavily on the import of soybeans. The concerns of the
sustainability and security of pig production have been increasing, due to the amounts of the raw
material used (e.g. soybean) currently, and if it continues to increase in the same magnitude. Also,
the increasing demand for SBM is associated with increasing demands for land use change lead to
environmental concerns (Fearnside, 2001). Thus, there is a need to find other applicable protein
sources to use as feed for pigs. In temperate environments, vegetable protein sources such as grain
legumes have been taken into consideration, while potential marine protein sources often have been
neglected, but could be considered as a feed ingredient for monogastric livestock. In a country like
Denmark, with a proportionally small area of cultivated land compared to the number of animals,
the surrounding sea could contribute with interesting protein sources such as seaweed, mussels,
crabs and starfish.
1.2 Demands in relation to feeding organic pigs
Organic farming is experiencing difficulties in feeding with 100% organic feed (Sundrum et al.,
2005; Nicholas et al., 2007; Grela et al., 2012). At the end of December 2014, the delegation from
the EU Organic Regulatory Board that allowed organic poultry and pig producers to include up to
3
Literature review
5% non-organic feed in the diets was supposed to cease. From then on, it would have been required
by all producers to feed a 100% organic diet for monogastric animals. Due to difficulties in
implementing this, the deadline has been extended to 31 December 2017 (Smith et al., 2014). Thus,
there is a need for possible strategies on how to cover the nutritional needs with organically
produced feed ingredients at different phases of production, ensuring high animal welfare and
health. The main problem is the scarcity of organic feed ingredients in Europe in proportion to the
demand of both energy and protein in concentrated feed ingredients that at the present are essential
when feeding monogastric animals (Smith et al., 2014). Furthermore, organic farming does not
accept the use of processed oilseed products, when subjected to solvent extraction processes (e.g.
hexane), or the use of genetically modified feed ingredients (e.g. SBM). In addition, it is prohibited
to supplement with crystalline amino acids (CAA) to optimise the diet for pigs according to their
AA requirements (Ministry of Food, 2015b). It is therefore crucial to generate suitable alternatives
to meet the pigs’ protein and AA requirements in organic production system according to the
Danish recommendations set by Tybirk et al. (2014).
The European organic research project ICOPP (Smith et al., 2014) looked at data on the organic
crop production, due to the request for using entirely organically feed for livestock. It was
concluded, that based on the protein supply and demand in Europe, it seems unrealistic that the
ICOPP countries (10 European countries) will be able to fulfil the organic protein demand in the
foreseeable future. Even if the countries try to produce protein crops relevant for the country in
question, it will be difficult to meet the indispensable AA requirements for the individual animal
category. The climate is the determining factor and the area of arable land for high-protein crops is
limited in the northern part of Europe, and considered as not suited for cultivation of the most
valuable high-protein crop; soybeans. In addition, the European Commission envisions more strict
regulation for feed, where a greater proportion of the feed should be produced on the farm. This
means, increased self-sufficiency for the organic farm or the product should be produced in the
region where the feed is to be used. For some producers, this can be complicated to achieve (Smith
et al., 2014). Factors such as metabolisable energy (ME) content, AA availability, digestibility, fibre
content and type and quantity of anti-nutritional factors (ANF), depending on the product in
question, will have an influence on the possible maximum inclusion rate of home grown protein
sources. For instance, a feed ingredient having a low protein content or deficient in one of the
indispensable AA, may be considered a valuable feed ingredient if other qualities are present, such
as being high in an indispensable AA important for the animal intended (Smith et al., 2014).
4
Literature review
The fundamental basis of the breeding material in conventional and organic pig herds are the same.
Therefore, the metabolic processes do not differ between the organic and conventionally reared
farm animals, and the pigs requirement for nutrients are equal in both rearing systems (Nicholas et
al., 2007). The Danish Energy Assessment System (abbreviated FE; 1 FE = approx. 7,380 kJ NE) is
designed so that the feed intake per kg growth is independent of the combination of feed ingredients
in the diet, provided that there is the same level of essential nutrients per FE. For growing pigs,
including piglets, growing and finisher pigs, the energy value FEsv is used. However, the
recommendations for an adequate nutrient supply generally follow similar guidelines in organic and
conventional feeding; the outdoor access required in organic farm systems leads to higher energy
requirements by the pigs but not necessarily higher micronutrient requirement. Concurrently, with
the restricted availability of indispensable AA in organic pig production, pigs may not be able to
fulfil their genetic potential for protein accretion. Even if they are offered a standard optimized feed
ration ad libitum, the living conditions can affect the performance level negatively (Nicholas et al.,
2007).
It has been pointed out by Grela et al. (2012), that organic feeding of pigs is mainly limited by the
supply of AA and some specific compounds as calcium (Ca), not often found in feed ingredients
grown at the farm. The chemical composition of organic feed ingredients may differ substantially
from the conventionally grown feed ingredients, especially regarding crude protein (CP) and
minerals, but also the energy value is slightly lower as compared to the conventional feeds (Grela et
al., 2012). Some organic feed ingredients have a higher crude fibre level and detergent fibre fraction
(ADF and NDF) than conventional ones, related to e.g. the small-sized seeds in grain that contain
more fibre and less starch. This can also refer to the depressed digestibility when having high crude
fibre content, that is inversely proportional to feed energy value (Grela et al., 2012). Furthermore,
roughage, fresh or dried fodder, or silage must be added to the daily ration for pigs, contributing to
the intake of crude fibre in pigs (Ministry of Food, 2015b).
To fulfil the need of AA, especially for piglets, it is proposed that it only can be achieved by
feeding with some natural non-agricultural feed ingredients like FM, that is not considered organic,
but is still approved with up to 5% in an organic diet (Ministry of Food, 2015b). An experiment
conducted to compare pigs fed with plant feedstuffs of organic origin and a diet enriched with FM
showed that the addition of FM significantly improved average daily gain (ADG), feed conversion
ratio (FCR) and carcass characteristics in the body weight (BW) interval 25-70 kg. The conclusion
5
Literature review
was that it was found reasonable to fortify typical organic mixtures with FM (Grela et al., 2012).
Though, despite the good effects, in Denmark, it is recommended not to feed pigs weighing more
than 40 kg with FM. This is due to the risk of rancidity and reduced storage stability of the pork
caused by high content of polyunsaturated fatty acids (PUFA) (Bejerholm et al., 1990).
Conventional and organically produced mussel meal are found to provide highly digestible AA
(Smith et al., 2014; Nørgaard et al., 2015), which can help improve the AA balance in feed for
organic piglets and is a potential substitute to FM. Mussel meal was found to be used as a
replacement for common protein sources in feed for growing/finishing pigs with maintained
production results regarding growth, feed efficiency and carcass quality (Smith et al., 2014).
Corresponding to the recommended maximum inclusion rate of FM, inclusion rate of mussel meal
should not exceed 5% in accordance with the allowed inclusion rate of non-organically feedstuffs,
as allowed only until 31 December 2017 (Smith et al., 2014).
An EU founded research project (EGTOP, 2015) with the objective to provide more knowledge on
how to achieve 100% organic rations in diets for organic livestock, has found it relevant to include
novel animal species such as insects, blue mussels and starfish as feed ingredients in the evaluation.
In same context, the Danish research project, “Biofouling and pest animals: sea stars” used starfish
as a protein rich feed ingredient for pigs, poultry and fish, and the results were promising
(Holtegaard et al., 2008). Starfish is not registered in the Community Catalogue of feed materials as
is the case with mussel meal. In the report by EGTOP (2015), it is shown that starfish may fit under
the code numbers 10.1.1 and 10.2.1 and can be used as feed ingredient in animal feed according to
Reg. (EC) 767/2009. Furthermore, according to Reg. (EC) 889/2008, Article 22 (e) as amended by
Reg. (EC) 505/2012 products from sustainable fisheries may be used as an organic feed ingredient.
It was concluded that feeding pigs with starfish should be included in the legislations, since starfish
fishery fulfil the environmental requirements for sustainable fishery. At the present, starfish is not
allowed as feed ingredient for pigs in EU, but the Danish authorities comprising
NaturErhvervstyrelsen, are working on getting starfish licensed as feed ingredient in the EU.
1.3 Environmental benefit
One of the largest pollution problems to the marine environment worldwide is the excess loading of
nutrients. Excess run-off primarily from agriculture of especially nitrogen (N) and phosphorus (P)
caused by e.g. low digestibility of protein in livestock, unbalance and oversupply of nutrients for
livestock, has accelerated the fluxes of these nutrients to coastal waters. Thus, fertilization of
6
Literature review
coastal ecosystems is a serious environmental problem (Petersen et al., 2014). An alternative to
terrestrial reduction measures, such as winter green fields, restricted period for applying fertilisers
and reduced fertilisation below economic optimum, is mussel production (Petersen et al., 2012).
Mussel farming is primarily used for producing mussels for human consumption, but can likewise
be used as a measure to remove nutrients from the marine environment (Edebo et al., 2000). The
concept of mussel farming as a tool for mitigation is that by harvesting the cultured mussels, the
mineral nutrients that are incorporated in the mussels will be removed and recycled when bound in
mussels and brought back from sea to land (Edebo et al., 2000; Petersen et al., 2014). Petersen et al.
(2014) concluded that the production of 50-60 t of mussels ha-1 mussel farm per year corresponds to
a potential nutrient removal of 0.6-0.9 t N and 0.03-0.05 t P per ha mussel farm per year. The cost
for nutrient removal in the study done by Petersen et al. (2014) was 105-150 DKK per kg N, which
did not include the potential of having an income by selling the mussels. If compared to e.g. sowing
catch crops in the spring, which has a price of 26-79 DKK per kg N and fertilization below
optimum with a price of 60-242 DKK per kg N, the cost for nutrient removed by mitigation mussels
is comparable to other land-based mitigation measures, making it a cost-efficient measure (Petersen
et al. 2014).
On equal terms with mussels, it can be suggested that starfish could also be used as a mitigation
tool, since they, contrary to fish, do not move over long distances, but stay in the same area most of
the time. Starfish have not yet been permitted as a mitigation tool, but have a great potential equally
with mussel farming, even without impact on the environment, e.g. sedimentation of organic matter
as is the case with mussel farms. Living starfish contain on average 1.65% N and 0.15% P of wet
weight. The removal of 10,000 t of starfish, would directly remove approximately 165 t N and 15 t
P from the coastal water (Petersen, personal communication, 2015). Such removal could be part of
achieving “good ecological status” in the Danish coastal waters, as is the goal for the European
Union Water Framework Directive (Anonymous, 2000). The usage of starfish in diets for
monogastric animals would therefore not only contribute with dietary protein, but also reduce the
environmental impact of the animal production by recycling of nutrients.
7
Literature review
2
Starfish
Starfish (Asterias rubens) are probably the single most significant predator of blue mussels living
on the seabed in natural mussel beds, bottom cultures or relaying areas. In areas like these, starfish
can cause significant decreases in the number of live mussels that are otherwise fished and used for
human consumption (Holtegaard et al., 2008). The occurrence of starfish in the inner Danish waters
has been increasing (Holtegaard et al., 2008) and still is (Kjølhede, personal communication, 2015).
Hence, the mussel fishermen in Limfjorden, Lillebælt and Isefjorden, have reported that the mussel
fishery has been plagued by substantial amounts of starfish that negatively affect the fishery. The
fishermen have suggested that if they fish the starfish, they could be of benefit elsewhere (Kjølhede,
personal communication, 2015).
2.1 Occurrence
The observed density of starfish fluctuate and is dependent upon the seabed, where in fine sand 331 individuals have been observed per m2 to 324-809 individuals/ m2 on alga carpets (Holtegaard et
al., 2008). Dare (1982) showed in his examinations in the Irish Sea, that in certain periods starfish
attained swarms of 300 to 400 individuals/m2, equivalent to a wet weight biomass of around 12 to
16 kg/m2. In relation to a translocation trial in Nissum Bredning in a part of Limfjorden, a swarm of
starfish devoured 72.7 t of blue mussels during a period of 7 months, indicating that starfish in
substantial extent can reduce the mussel population (Holtegaard et al., 2008). The size of the
population of starfish in all Danish waters is not known, but examination done in 1996 in the central
part of Limfjorden showed an estimated population size of 10,000 t (Holtegaard et al., 2008). The
impact study done by Nielsen et al. (2014) on request of NaturErhvervstyrelsen in Denmark,
showed that a fishery of 7,000 t starfish in the period 2014-2015 as proposed in the fishing plans
would constitute 18-27% of the population in Løgstør Bredning, the greatest part of Limfjorden,
depending on the method used to determine the population size. DTU Aqua assessed, in proportion
to the total population of starfish in Limfjorden, that fishing 7,000 t along with fishing 2,000 t in
Lovns Bredning, the south-eastern part of Limfjorden, would be sustainable compared to the whole
population in Limfjorden (Nielsen et al., 2014). There is no well-documented data related to the
population size in Limfjorden, and the estimate of the population size is therefore considered with a
good amount of uncertainty. The increase in population size during the latest years entail that the
assessment of the impact of fishing starfish is not related to any insecurity when taking the whole
population in consideration (Nielsen et al., 2014). Therefore, a fishery of 10,000 t of starfish per
8
Literature review
year would be possible. For the fishermen to have an economically sustainable fishery of starfish,
the estimated density of starfish on the seabed should be 1.5 kg/m2 (Nielsen et al., 2014).
The predation on starfish is rather limited and the population seems primarily controlled by
environmental considerations and amount of feed available. Starfish have not been characterised as
a species worth for preservation, and can on the contrary affect biogenic reefs, constituted by thick
layers of mussels, negatively (Nielsen et al., 2014). In Denmark, the natural mussel beds are
considered as a part of these biogenic reefs. With the documented predation on the natural mussel
beds, the starfish pose a potential threat to biogenic reefs (Nielsen et al., 2014).
2.2 Handling and use of starfish
During the first 30 hours after the starfish have been caught, depending on the handling of the
starfish, it can lose up to half of its bodyweight in fluid (Holtegaard et al., 2008). The colour of the
fluid that is lost indicates that the starfish undergoes a process with running alterations in which of
the ingredients in starfish is lost with the fluid. The initial bright fluid might indicate that it is water
from the hydrocoel (a complex water vascular system unique for Echinodermata) that is lost
together with fluid from the body cavity. The increasing proportion of brown particulate material in
the fluid indicates an increasing compression and decay of the digestive glands that are in the same
brown colour. This stage is reached not more than 5 hours after catch, where the starfish has lost a
fourth of its bodyweight. 30 hours after catch, a vivid red-orange colouring of the lost fluid
indicates that a part of the pigmentation of the starfish is lost through the fluid. The amount of fluid
lost is greatest immediate after catch and drops until about five hours after collection. Afterwards,
the loss of fluid is rather constant over the next 24 hours (Holtegaard et al., 2008). Because of the
unknown knowledge about the accurate loss of nutrient from the starfish after catch, it is important
to take that in consideration when storing before and after transportation to the processing of the
starfish if the product is intended to use as a feed ingredient.
It has been well-known for decades and around the world, that starfish are a serious pest of both
mussels and oyster-beds. Hutchinson et al. (1946) reported that starfish was a serious pest of oysterbeds in the coastal waters of the north-eastern United States, and were captured in considerable
quantities by fishermen engaged in oyster culture. The starfish were here grounded into meal and
sold for either food for farm animals or used as fertilizer. In the same study, it was also reported that
during the First World War in Europe, starfish were mixed with oyster-shells and used as fertilizer
for acid soils in France. In Denmark, during the period 1959 to 1980 there was a small fishery for
9
Literature review
starfish in Limfjorden, where the starfish were grounded into meal and some mixed with herring
meal and fed for pigs in Denmark (Kjølhede, personal communication, 2015). The greatest part of
the SM was, however, exported to West-Germany, where it was mixed with FM and fed for poultry
(Holtegaard et al., 2008). Unfortunately, all existing data about this has gone lost. Due to more
accessible resources available, together with the fear of mad cows disease when mixed with other
sources of bone meal, the production was terminated. As other marine resources have been scarce,
the interest for alternative, unutilized resources have increased. The use of starfish is not necessarily
limited to feed for monogastric animals, since it has also been speculated as fertilizer, product for
biogas plant, utilization of their spawn and extraction of antibacterial peptides as found in
invertebrates. Levin et al. (1960) pointed out that the economic problems of utilizing starfish
involved low-cost fishery providing an inexpensive raw material, comparable processing costs per
unit of protein like the conversion of fish into FM and practical use of SM in for instance feed for
animals.
For more than three years, the mussel fishermen in Limfjorden have been using a starfish seine to
remove the starfish from the seabed, to reduce the occurrence of starfish and their predation on
mussels. Some of these starfish were carried to Cux-haven in Germany and processed into meal,
while others were pressed in a clamp, by which a fluid fraction came, giving two different products
of starfish. Chemical analyses of the products led to a project that was to determine the chemical
composition and digestibility of SM in pigs (Nørgaard et al., 2015) and poultry.
2.3 Chemical composition of starfish
The biochemical composition of the starfish changes during the annual reproductive cycle and in
general, the biochemical composition of the ovaries gives a good indication of the changes in
nutrients of the total starfish. In the ovary of starfish, relatively low levels of carbohydrates and high
levels of protein and lipid are found (Oudejans and Vandersluis, 1979). During yolk deposition
(vitellogenesis), the process of yolk formation through nutrients being deposited in the oocyt, the
main weight increase of the ovary occurs. This increase starts in the early autumn and continues
until maturity in late spring (April/May) when the starfish spawn. In contrast, the ovarian growth is
relatively small during pre-vitellogenesis (June to September) (Oudejans and Vandersluis, 1979).
Oudejans and Vandersluis (1979), found that the contents of total lipids, total carbohydrates, free
AA and proteins shows a rectilinearly increase, contributing to ovarian growth. In relation to the
size of the ovaries, the free AA level is rather constant during the development (Oudejans and
10
Literature review
Vandersluis, 1979). Levin et al. (1960) found indication of that all the constituents of starfish are
variable and depend largely on size, freshness, season and environmental factors associated with the
specific samples. The knowledge of the biochemical composition of the starfish tells when it is most
favourable to fish them, for instance in relation to use as feed ingredient for monogastric livestock,
where it is desirable to have a high CP content. Table 1 confirms the findings done by Oudejans and
Vandersluis (1979), that the total AA level and relative distribution of AA in proportion to CP is
rather constant during the year, while the content of CP varies the lowest in June until autumn and
greatest in May following the starfish reproduction cycle. Fishing starfish in May where the CP
level is greatest, will in relation to using starfish as a feed ingredient be of greatest interest.
Table 1 - Chemical composition, total amino acid (AA) content and relative distribution of AA in proportion to crude protein (CP) in
g/kg dry matter in fresh starfish and starfish meal (SM). The data from the fresh starfish is collected on 6 different days throughout
year 2007 and modified from Holtegaard et al. (2008). The data from SM is on sample date 050107 from Holtegaard et al. (2008) and
sample date 110514 and 040115 is data from the current STARPRO project.
Fresh starfish
May
Jun
Aug
May
Nov
Apr
07
07
07
07
07
14
15
Dry matter
242 239 243 222
233
243
284
936
961
935
CP
361 446 459 423
536
347
379
520
383
452
65
89
59
50
68
91
96
Crude ash
470 395 374 455
313
483
430
325
421
350
Ca
137 117 130 137
84
157
146
104
130
106
P
4,6
6,1
7
5,9
9,6
4,3
4,3
19,2
6,3
7,3
Cys
4,7
5,8
5,7
5,7
6,1
4,6
5
5,4
4,8
4,7
5,4
His
5,6
7,9
7,1
6,7
7,4
5,69
6,3
6,7
8,9
6,1
7,3
Ile
12,4 16,6 15,9 14,6
16,9
12
13,5
14,6
19
14,5 14,8
Leu
18,1 24,1 23,1 21,5
25,5
17,6
19,6
21,4
30,4
21,4 24,2
Sample date
Nov
06
Jan Feb Mar
SM
07
07
Average
Item, g/kg dry
matter
Crude fat
53
52
75
Total amount of
AA
11
Literature review
Lys
Met
20,8 28,2 28,3 26,6
6,6
8,3
31,4
20,3
21,3
25,3
30,6
20,6 26,2
8,5
7,5
8,7
6,2
7,5
7,6
11,3
8,1
9
Phe
10,5 13,8 13,4
14
16,3
10
12,1
12,9
17,1
12,5
15
Thr
15,6 19,8
19 17,6
20,3
14,7
18
17,9
20,6
4,3
4,1
18 19,6
Trp
3,3
3,9
4,3
3,3
3,7
3,8
3,9
3,8
4,8
Tyr
9,8 12,9 12,4 12,7
14
9,3
10,8
11,7
13,5
13,1
Val
15,8 20,7 18,7 19,7
22,5
14
16,5
18,3
22,7
17,8 18,9
Relative
distribution of
AA in proportion
to CP
His
1,6
1,8
1,5
1,6
1,4
1,6
1,7
1,6
1,6
1,6
1,6
Ile
3,4
3,7
3,5
3,5
3,2
3,5
3,6
3,5
3,4
3,8
3,3
Leu
5
5,4
5
5,1
4,8
5,1
5,2
5,1
5,5
5,6
5,4
Lys
5,8
6,3
6,2
6,3
5,9
5,9
5,6
6
5,5
5,4
5,8
Met
1,8
1,9
1,9
1,8
1,6
1,8
2
1,8
2
2,1
2
Met+Cys
3,1
3,2
3,1
3,1
2,7
3,1
3,3
3,1
2,9
1,2
1,2
Phe
2,9
3,1
2,9
3,3
3
2,9
3,2
3
3,1
3,3
3,3
Phe+Tyr
5,6
6
5,6
6,3
5,6
5,6
6
5,8
5,5
Thr
4,3
4,4
4,1
4,2
3,8
4,2
4,7
4,2
3,7
4,7
4,3
Trp
0,9
1
0,9
0,9
0,8
1
1
0,9
0,7
1
1,1
Val
4,4
4,6
4,1
4,7
4,2
4
4,4
4,3
4,1
4,6
4,2
Determinations of certain biologically important elements have been made on different species of
the genus Asterias, found in their respective area in the world. Starfish contains various secondary
metabolites including steroids, storoidal glycosides, anthraquinones, alkaloids, phospholipids,
peptides, and fatty acids (FA). These chemical constituents exhibit cytotoxic, hemolytic, antiviral,
antifungal and antimicrobial activities. Therefore, starfish is of great interest as a natural bioactive
marine product and presumably in a wide variety of pharmacological activities (Dong et al., 2011).
Asterias rubens is native to the north-east of Atlantic Ocean, and is the most common starfish found
in Danish waters. Asterias rubens produces the secondary metabolite asterosaponins, that are
pentaglycoside or hexaglycoside sulfated steroids. These molecules are interesting because of their
12
Literature review
hemolytic, cytotoxic, anti-bacterial, anti-fungal, anti-viral and anti-tumor properties (Demeyer et al.,
2014). Secondary metabolites of interest have also been found in Asterias rollestoni Bell, one of the
most commonly distributed starfish in China (Zhang et al., 2013). Gudbjarnason (1999) mentions
that extract from the starfish Ctenodiscus crispatus showed considerable cytotoxic activity. The
pharmacological activities the literature of this area indicate that starfish have, can be of great value,
for instance if used as feed ingredient to livestock, e.g. if the cytotoxic effect would be transferred
to the animal. Therefore, starfish not only in Scandinavia can be of great interest for the animal feed
industry.
Furthermore, toxicity of starfish has been described. Asakawa et al. (1997) found that Asterias
amurensis inhabiting the Hiroshima Bay in Japan was toxified with paralytic shellfish poison (PSP).
Paralytic shellfish poison is a most hazardous marine toxin and cause sporadic food poisoning in
humans around the world, and could potentially cause the same condition in pigs. The toxification
of starfish with PSP happens through predation on mussels. Paralytic shellfish poison is produced
by phytoplankton such as Alexandrium tamarense, accumulated in filter feeding bivalves such as
mussels, and then transferred to carnivorous invertebrates. The phytoplankton has several times
been the cause of closed areas for commercial fishery on blue mussels at the east coast in Denmark,
e.g. Limfjorden. The occurrence of phytoplankton in Danish waters is under constant surveillance
by the Danish monitoring program on toxic and potentially toxic algae/phytoplankton and algae
toxins in bivalve molluscan shellfish in relation to the Danish mussel fishery, and therefore there is
no risk of any toxicity of starfish in Denmark (Ministry of Food, 2015a).
2.4 Starfish as feed ingredient
Several decades ago, as mentioned previously, experiments were conducted to determine if starfish
was a possible substitute for other well-known protein sources in poultry. This was done both
because of the abundance of starfish, but also because of the need for alternative protein sources as
a replacer for e.g. FM. Growth has been used as a criterion of measurement when determining the
practical value of SM (Bird, 1946; Heuser and McGinnis, 1946; Morse et al., 1946; Ringrose, 1946;
Stuart and Hart, 1946; Whitson and Titus, 1946; Levin et al., 1960). A summary of the published
papers on the chemical composition of SM and experiments determining the practical value of SM
in feeding poultry is presented in Table 2. It is rather difficult to compare data on chemical
composition of SM from different experiments because of the difference in species of the genius
Asterias, time of fishing in the reproductive cycle of the starfish and difference in the biochemical
13
Literature review
analyses. The same goes for experiments related to growth performance because of the difference in
chemical composition of SM, experimental conditions, breed and age of the animal, management,
etc. SM as product varies also in preparation method. Some have used air- or sun-dried starfish
grounded into meal (Stuart and Hart, 1946; Whitson and Titus, 1946) and others, defatted SM
(Levin et al., 1960). The effect of SM in diets for pigs on performance has not been reported.
Table 2 - Chemical composition and practical value of starfish meal (SM) in poultry feeding using growth as a criterion of
measurement.
Chemical
composition
SM
CP: 24.9%
CP: 34%
Ca: 16.9%
P: 0.43%
CP: 34%
Ca: 16.9%
P: 0.43%
CP: 33.63%
Ca: 15.14%
P: 0.48%
CP: 34%
Ca: 16.9%
P: 0.43%
CP: 34%
Ca: 16.9%
P: 0.43%
CP: 30.7%
Ca: 17.6%
P: 0.35%
a
SM% in diet
Age of
chickens
(weeks)
0 (reference rationa)
10
20
40
0
3
6
0 (3% fish meal)
3
6
12
0 (2.5% fish meal)
4
8
0 (4% fish meal)
9
18
0
4
2-4
2.5
4
7.5
8
12
3.5-6
0-9
0-8
0-8
0-6
0-12
Semi-purified reference ration - described in paper.
14
Average
final BW
(g)
594
533
482
376
846
949
934
699
700
673
441
854
803
816
254
209
170
1,283
1,332
450
399
351
297
243
Average
feed
consumed
0.654
0.621
0.579
0.542
2.35
2.13
2.12
5.99
6.27
Gain to
feed
Reference
0.539
0.468
0.415
0.247
0.336
0.350
0.337
(Stutz and
Matterson,
1964)
0.346
0.348
0.350
0.209
0.171
0.140
0.467
0.471
(Bird,
1946)
(Heuser
and
McGinnis,
1946)
(Morse et
al., 1946)
(Ringrose,
1946)
(Stuart
and Hart,
1946)
(Whitson
and Titus,
1946)
Literature review
Though older literatures rather limited information of how the experiments have been conducted,
and some ostensibly important results have been led out, the findings in Table 2 gives an impression
of that SM is an acceptable alternative protein source for poultry.
The amount of SM tested in the experiments range from 2.5% to 40% of the diet. Bird (1946)
recommended 3% SM inclusion in the diet, Whitson and Titus (1946) recommended 2.5-5%
inclusion, where Morse et al. (1946) recommended 4% inclusion level of SM. Moreover, Heuser
and McGinnis (1946) found that the maximum inclusion level was 6%, and 3% SM was equally as
good as 3% FM. While on a 12% SM ration, very poor results were obtained. It was reported by
Ringrose (1946) that SM is 83% as effective as FM when 9% of SM was used in a 13% protein
ration. The same author found that depressed growth and high mortality was the result of 18% SM
in an 18.5% protein ration. Ringrose (1946) also concluded that the depressed growth and high
mortality were undoubtedly caused by the high Ca compared to the low P level, giving a wide
calcium to phosphorus ratio (Ca:P) in the feed used. Furthermore, it was noted in a metabolism
study done by Stutz and Matterson (1964) that when the level of SM increased from 10% to 40%,
greater growth depression was experienced with an average BW for the whole experimental period
of 533 and 376 grams, respectively (see Table 2). Levin et al. (1960) concluded that a protein
concentrate prepared from a defatted, HCl washed SM exhibits high protein quality values,
comparable to good quality FM. Moreover, the Ca level of the HCl washed SM was sufficiently
reduced to allow incorporation into the diet, providing 10% protein without raising the dietary Ca
level (Levin et al., 1960). Their experiment showed that mixtures of 20% SM and 80% FM, and
30% SM and 70% FM, respectively, had higher protein quality values than FM alone in a ration
with a 10% dietary protein level. When added at levels of 3-6% to purified (less variable nutrient
concentrations) or practical diets, while maintaining the same dietary Ca level, defatted SM is on a
protein basis equal to FM, maintaining the same dietary Ca level.
In a digestibility study done by Nørgaard et al. (2015), SM was analysed for sand (acid-insoluble
ash) to explain the high ash content of SM. They found SM to contain 47 g Ca, 26 g P, 24 g Cl and
18 g Na per kg DM, meaning that only about half of the ash content in SM is constituted by Ca, P,
Cl and Na. The remaining fraction of the ash content was not identified, but could be silica (SiO2; a
major constitute of sand) (Nørgaard et al., 2015). The high ash content was also noted by Stuart and
Hart (1946), Levin et al. (1960), and Stutz and Matterson (1964), but the actual composition of
minerals in the ash and possible effect on the animal fed a diet high in ash, was not reported.
15
Literature review
The preceding indicates that starfish can be a possible substitute for other well-known protein
sources because of their abundance, their biochemical composition and possible pharmacological
activities. It can be questioned if it will be possible to use starfish as the sole protein source as an
alternative to the most common used protein sources as SBM, due to the high Ca content that
apparently limits the possible inclusion level. Thus, there is a need for further investigation of
starfish as an alternative protein source for monogastric livestock, especially pigs.
3
Nutrient requirement of piglets
Over the years, genetic selection of pigs has increased capacity for lean tissue growth (Tausen,
2012). Simultaneously, the rate of fat deposition has been reduced, and capacity for feed intake
declined. A high voluntary feed intake (VFI) is necessary for making use of the capacity for rapid
lean tissue growth, whereas limited fat deposition and efficient feed utilization requires a low VFI.
The pig’s inherent maintenance requirement and desire to retain body protein and fat is linked to its
VFI. The genetic selection for lower fat deposition in pigs has not changed the genetic drive to
consume the required amounts of nutrients and energy, but the pigs having lower energy
requirements, has led to decreased VFI (Tausen, 2012).
3.1 Energy requirement
The energy content of feed for piglets has been reduced during recent years - mainly due to the
higher barley content and less addition of fat in the compound feed compared previously. Milk and
fish products are also used to a lesser extent than earlier (Rasmussen and Vinther, 2015). Piglets are
in an energy dependent phase of growth, and their requirement for ME can roughly be ascribed to
the sum of energy requirement for maintenance, thermoregulaion, and energy deposition in body
tissue. The energy requirement for piglets are normally stated for both maintenance and production
combined. A function of BW (maintenance) and the proportion of protein and lipid in gained
tissues, determinates the energy need for growth (NRC, 2012).
As estimated by Rasmussen and Vinther (2015), piglets achieve the best performance, i.e. maximal
growth and feed efficiency, at an energy content of 1.08 FEsv/kg diet at a BW of 9.5-31 kg. The
maximal average daily feed intake (ADFI) is achieved at an energy content of 1.17 FEsv/kg feed,
whereas the highest ADG is achieved at 1.12 FEsv/kg feed. Indicating, that different energy
contents is needed for different parameters. An increment in the energy content with 1 FEsv/100 kg
16
Literature review
feed in the interval 100 to 123 FEsv/100 kg feed gave a significantly reduced feed efficiency of
0.006 FEsv/kg growth. The price of a FEsv determines what energy content the pigs should be fed,
and the cheaper the feed is the more shifting towards higher energy content. The recommended
energy content in feed for piglets with BW of 9.5-31 kg was found to be between 1.07 and 1.12
FEsv/kg feed (Rasmussen and Vinther, 2015).
3.2 Protein and amino acids requirement
A piglet’s requirement for N is expressed on basis of net energy (feed units; FE) in the Danish feed
evaluation system. Beside requirement for N, the dietary supply of N or CP also needs to meet the
requirement for AA. The physiological use of AA is divided in two distinct, but dependent uses;
AA for maintenance and AA for protein accretion. The indispensable AA are a main determinant of
the level of production that can be obtained, and are therefore of great importance. Sufficient energy
supply through carbohydrates and fat from the diet is a prerequisite for optimal utilization of dietary
proteins. The Danish recommendations are based on having an appropriate balance between energy
and protein expressed as the pig’s need for protein and AA on an energy basis; in other words, as
gram digestible product per FEsv (Nørgaard et al., 2012). If there is an imbalance in the AA profile
or if the pigs are fed in excess amount of N, the surplus will be secreted as urea in the urine.
Commercial herds and controlled experiment conditions ascertain that the risk of diarrhoea after
weaning increases with increasing protein level in the diet. Together with both source and level of
dietary protein, these are known to influence enteric health in piglets (Heo et al., 2013; Tybirk et al.,
2014). In Denmark, so-called low-protein diets for piglets have a total protein content of 18-20%
(Maribo, 2010), amounting 145-158 g/FEsv, 140-152 g/FEs and 140-154 g/FEsv digestible CP,
respectively, for pigs of 6-9 kg, 9-15 kg and 9-30 kg BW, respectively. Normal simple protein diets
for piglets contains 20-22% of protein, amounting 158-170 g/FEsv and 150-162 g/FEsv digestible
CP, respectively, for pigs of 6-9 kg and 9-30 kg BW (Maribo, 2010). The dietary CP reduction with
CAA inclusion can effectively reduce N excretion, ammonia emission and precisely match the pig’s
AA requirement (Zervas and Zijlstra, 2002; Norgaard et al., 2014).
To optimize the use of limited resources, especially protein sources, it is necessary to adapt the level
of AA given to the pig followed the protein accretion capacity. A suboptimal supply will reduce the
performance of the pig while excess supply of AA will not have an increasing effect on
performance (Sundrum et al., 2005). The Danish recommendations for a piglet’s requirement for
individual indispensable AA is given by Tybirk et al. (2014).
17
Literature review
3.3 Mineral requirement
Calcium and P are minerals that have an important role in the development and maintenance of the
skeleton, together with many other physiologic functions in the body. When formulating diets for
pigs, it is necessary to consider an appropriate Ca:P for an adequate absorption and utilization of
both minerals, since excess or deficiency in one of the minerals will cause impaired utilization of
the other (Gonzalez-Vega and Stein, 2014). However, dietary Ca and P levels are generally
formulated to achieve optimum growth instead of maximum bone mineralization, which is, of great
importance for the pig’s health. The amount of P needed for optimum growth is lower than for
maximum bone mineralization (Maxson and Mahan, 1983; Koch et al., 1984; Varley et al., 2011).
Furthermore, the P level in diets is often low in the attempt to reduce emission of P to the
environment (Lenis and Jongbloed, 1999; Metzler et al., 2008). Calcium and P share a mutual
antagonism and both have antagonistic effects on other elements (Peo, 1991). It was indicated by
Peo (1991) that adequate level of Ca and P for pigs in every growth phase is dependent upon: a) an
adequate level of both Ca and P in an available form in the diet, b) an appropriate ratio of available
Ca and P in the diet, and c) adequate vitamin D present for Ca to be absorbed. In many commercial
diets Ca is frequently found in excess and the various Ca:P may result in different effects depending
on the dietary P level.
The Danish Pig Research Centres’ recommendations in diets for piglets with BW from 6 to 9 kg
and 9 to 15 kg is, respectively, 7.0 g and 8.5 g Ca/FEsv without phytase added to the diet, and when
phytase is added, 6.5 g and 8.0 g Ca/FEsv (Tybirk et al., 2014). The content of digestible P in feed
cannot be controlled, therefore, the diets content of digestible P must be considered in the context of
the total content of P. The recommended minimum content of total P for pigs with a BW from 9 to
30 kg in diets added phytase is 5.2 g tP/FEsv when phytase is added equalling 100% dose, and 4.9 g
tP/FEsv when phytase is added equalling 200% dose in a diet containing grain and SBM, where the
source of P is monocalcium phosphate (Tybirk et al., 2014). So, the requirement for P is lower
when phytase is added to the diet. The figures are given as the pigs’ requirement, plus a safety
margin. It is therefore not recommended to supply these nutrients in surplus, since e.g. Ca interacts
with some micro and macro minerals and can impede absorption of these minerals.
18
Literature review
4
Practical feeding around weaning
4.1 The transition of weaning
Weaning from the sow is one of the most stressful events in the pig’s life, where the pigs experience
nutritional, psychological, environmental, and social challenges that can predispose the pig to
subsequent diseases and production losses (Pluske et al., 1997; Campbell et al., 2013; Heo et al.,
2013). When the piglet is weaned, the piglet must adapt abruptly from the sow’s milk that is highly
digestible, palatable and high in protein, fat and lactose to a less digestible, palatable starch-based,
solid dry diet containing complex protein and carbohydrate including various anti-nutritional factors
(Heo et al., 2013). The consequence is usually that VFI is sharply reduced initially after weaning
and the piglet becomes malnourished with reduced transient growth rate (Pluske et al., 1997).
Approximately 50% of weaned piglets consume their first feed within 24 hours post-weaning;
unfortunately, in about 10% of the weaned piglets, weaning anorexia persists for up to 48 hours
(Heo et al., 2013). By the end of the first week post-weaning, it is estimated that ME intake is about
60-70% of pre-weaning milk intake and it takes approximately 8-14 days for the piglet to recover
the pre-weaning ME intake level (Campbell et al., 2013). As reviewed by Lalles et al. (2007), even
a minimal consumption of feed in the suckling period will stimulate VFI after weaning. The
positive relationship between cumulative feed intake during day 0-3 post weaning and villous
height confirms the importance of VFI in this period. Thus, to stimulate VFI and thereby energy
intake post-weaning, the ingredients in the feed must be highly palatable to stimulate feed intake,
highly digestible, and contain a high net energy (NE) concentration.
4.2 Diet characteristic and protein sources
The overall aim in the grower period is to produce healthy pigs with a high daily gain at the lowest
expense for feed and medicine (Maribo, 2010). Feed for piglets should be compounded so that the
piglet’s requirements for nutrients and energy are fulfilled. Furthermore, to achieve maximum
growth performance the dietary ingredients selected, should match to the pig’s digestive capacity.
In growing pigs, the feed cost account for more than 60% of total production costs. A change in the
feed composition should be assessed in proportion to if it will pay in the form of better performance
and health in relation to the price of the feed (Maribo, 2010).
Commercial diets for piglets with a BW of 9-15 kg differ among feed companies in content and
amount of the different feed ingredients. The Danish Pig Research Centre has set a line of
19
Literature review
recommendations for the maximum amount of feedstuffs in diets for 5 week old piglets. Principally,
the diet should contain highly digestible protein sources such as FM, soy protein, potato protein,
whey powder, shimmed milk powder and similar products (Maribo, 2010). Table 3 gives an
overview of the guiding figures from the Danish Pig Research Centre (Jørgensen, 2012) for
maximum use of the most used feedstuff comprising grain and protein sources together with their
content of CP and the standardized ileal digestibility (SID) of CP.
Table 3 - Extract of guiding figures from the Danish Pig Research Centre for maximum use of feedstuff in diets (percent of kg feed)
for piglets from 5 weeks of age (Jørgensen, 2012). Only main ingredients as grain and protein sources often used in diets for
weanlings pigs is presented. Crude protein (CP) (% of dry matter) and standardized ileal digestibility (SID) of CP is presented to
show difference between feed ingredients (VSP, 2015).
From 5 weeks
CP
10
SID of CP
Barley
70
75
Wheat
70
10
82
Oat
50
11
66
Soy bean meal, dehulled toasted
20
48-56
86-88
Potato protein concentrate
5
85-88
89
Fish meal, all types
12
76
90
Salmon protein concentrate
10
70
92
Skimmed milk powder
25
34-37
94
Whey powder
25
9-13
85-92
Soy protein concentrate
25
56-66
82-90
Palm oil
7
0
0
As indicated in Table 3, protein is available in a variety of dietary sources. These include
ingredients of vegetable and animal origin. Evaluation of how good a protein source is is
accomplished by determining the quality and digestibility of the protein (Hoffman and Falvo,
2004). The quality refers to the availability of the AA that the protein supplies and digestibility deal
with the proteins capacity of being easy to digest. All dietary protein sources of animal origin are
considered to be complete proteins, which mean that the protein contains all of the indispensable
AA. Vegetable protein sources are considered incomplete since they generally are deficient in one
or more indispensable AA. Thus, to get all the protein needed solely from vegetable sources, it is
20
Literature review
needed to consume a variety of legumes, fruits, grains and vegetables to ensure the right
consumption of all the indispensable AA (Hoffman and Falvo, 2004). This is a difficult task when
composing diets for piglets. Digestibility of protein involves rating how well the body can
efficiently utilize protein of dietary sources. Typically, animal protein has a higher digestibility than
vegetable protein sources (Hoffman and Falvo, 2004). Animal proteins like FM, whey and spreydried plasma provide the highest quality, primarily due to the composition of indispensable AA and,
therefore, the completeness of the protein source. Despite that these proteins are associated with
high intakes of saturated fat, there have been a number of studies that have demonstrated the
positive benefits of animal proteins. On the contrary, intake of vegetable proteins will reduce the
intake of saturated fats and provide other nutrients such as fibre and phytochemicals. However,
some vegetable sources of protein are recommended not to use for piglets such as rye, beet pellets,
peas and sunflower meal (Maribo, 2010).
As described earlier, SBM is a commonly used high-quality protein source for pigs. However, when
SBM is fed for piglets, digestive disturbances can be observed. Presence of trypsin inhibitors,
antigenic soy proteins, and indigestible carbohydrates as oligosaccharides, may be contributors to
the problem often experienced as diarrhoea (Pluske et al., 1997; Cervantes-Pahm and Stein, 2010).
Other ANF present in SBM beside trypsin inhibitors, such as lectins and tannins, have been
reported to increase losses of endogenous proteins at the terminal ileum. Furthermore, decreased
hydrolysis of protein and absorption of AA may be related to these ANF. Therefore, only limited
quantities of SBM are included in diets for piglets, by which animal-derived alternatives as milk
proteins and FM are widely used (Cervantes-Pahm and Stein, 2010).
Piglets profit from dairy products known to have a beneficial effect on VFI, growth performance,
feed efficiency and health, due to the high palatability and high SID of energy and protein (Lalles et
al., 2007; Cervantes-Pahm and Stein, 2010).
Spray-dried plasma is a good protein source for piglets and is commonly used in countries where
they wean piglets earlier than 24-31 days of age. Spray-dried plasma is a highly digestible protein
source and it is presumed that the immunoglobulins in plasma contribute to the maintenance of the
mucosal integrity and the reduction of inflammatory response in the intestine, helping the piglet to
resist bacterial presence (Torrallardona et al., 2003; Nofrarias et al., 2006). Spray-dried plasma has
not been included in Table 3 since The Danish Pig Research Centre recommend phasing out the use
21
Literature review
of spray-dried plasma with regard to the potential risk of Porcine Epidemic Diarrhoea (PED)
followed the use of the product (VSP, 2014).
Fish meal is considered a very digestible protein source with a high content of vitamins, minerals,
and favourable AA composition (Jonsdottir et al., 2003). However, the quality of FM varies
depending on the species of fish, the freshness before processing and the way the fish is processed
into meal (Kim and Easter, 2001). A study found that gain to feed ratio (G:F) was higher in pigs fed
a diet containing 5 rather than 2.5% mackerel FM (Kim and Easter, 2001). Fish meal has a high
content of PUFA, including the n-3 FA C20:5 (EPA; Eicosapentaenoic acid), and C22:6 (DHA;
Docosahexaenoic acid), that can lead to higher content of PUFA in the carcass fat. PUFA’s can give
rise to rancidity and reduced storage stability leading to undesirable off-flavours and off-odours in
the meat (Hertzman et al., 1988; Jonsdottir et al., 2003; Hallenstvedt et al., 2010). A study
conducted with pigs having an initial BW of 25 kg, found that supplementation of FM significantly
increased the content of both n-6 (linoleic, eicosadienoic, and docosadienic acids) as well as n-3
(linolenic acid) in the longissimus dorsi muscle and at the same time decreased the content of
stearic acid (Grela et al., 2012). Cho and Kim (2011) reported that the n-3 PUFA has antiinflammatory properties and benefits to the immune system, whereas Thies et al. (1999) reported
that n-3 PUFA have been shown to downregulate immune function in humans, laboratory animals
and also pigs. Nevertheless, FM is considered one of the best protein sources for piglets (Kim and
Easter, 2001), and no adverse effect on immunity on piglets have been reported. Jørgensen (2004)
reported that a diet for piglets without added FM, did not significantly affect productivity or feed
costs. Diets containing a composition of soy protein concentrate, potato protein concentrate, whey
powder and/or skimmed milk powder, were good alternatives to diets containing FM. It is worth a
mention that diets without FM were added several different protein sources compared to only a few
when FM was used, thereby increasing the need for several different feed ingredients when not
using FM. Fish meal supply with a good composition of indispensable AA and possibly improve
palatability (Jørgensen, 2004).
As mentioned before, SM can be considered as a new and alternative high-quality source of protein.
Both the chemical characteristics and the results of SID of SM obtained by Nørgaard et al. (2015),
points toward a potential use of SM in pig diets. It was concluded that CP content (700 g/kg DM)
and indispensable AA except lysine and leucine in SM were comparable to that of FM. Moreover,
22
Literature review
the SID of CP (0.80) and AA (0.84) were higher than in commercial fish silage and could be of
interest as feed ingredient for piglets.
5
Final remarks and conclusion of literature review
-
Starfish in diets for monogastric animals will both contribute with dietary protein but also
reduce the need for increasing land use change and minimise the environmental impact of
the animal production by recycling of nutrients.
-
Animal proteins e.g. SM provides a high quality of protein, primarily due to the composition
of indispensable AA and, therefore, of great interest as alternative source of protein
compared to vegetable sources.
-
Starfish meal is comparable to FM in quality and can be a realistic alternative to many wellknown protein sources.
-
The numerous chemical components that exhibit e.g. antimicrobial, antiviral and antifungal
activities found in starfish can be of great interest, if they show any significant bioactivity
effect on pig performance.
-
Starfish meal can contribute with a potential organic feed ingredient that meets the organic
production standards and concept and help to accomplish the implementation of a 100%
organic diet for monogastric animals by the end of 31 December 2017.
-
There may be a potential of feeding organically reared piglets with SM, especially owing to
the highly digestible AA, which can contribute to improve the AA balance in feed for
organic piglets.
The literature review indicates that there is a need for, but also a possibility of producing new highquality protein alternatives to piglets comprising starfish. Starfish is a promising protein source,
however, it is not tested in pigs yet.
23
24
Manuscript to be submitted
1
Starfish (Asterias rubens) as feed ingredient for piglets
2
3
P. Sørensena*
4
5
a
6
Denmark
Department of Animal Science, Aarhus University, Foulum, P.O. Box 50, DK-8830 Tjele,
7
8
Abbreviations: AA, amino acids; ADFI, average daily feed intake; ADG, average daily gain;
9
BW, body weight; Ca:P, calcium to phosphorus ratio; CP, crude protein; DM, dry matter; FM,
10
fish meal; G:F, gain to feed ratio; PUN, plasma urea nitrogen; SBM, soy bean meal; SID,
11
standardized ileal digestibility; SM, starfish meal; SPC, soy protein concentrate.
12
13
*
Corresponding author: E-mail address: [email protected]
14
15
ABSTRACT
16
The effects of including starfish meal (SM) as an alternative protein source in diets for piglets on
17
performance, faeces characteristics and plasma parameters were investigated. Four diets were
18
formulated to contain different protein sources; fish meal (FM), soy protein concentrate (SPC)
19
and two levels of SM (SM5% and SM10%). All diets contained 174.4 g soybean meal (SBM)/kg
20
and were supplemented up to 166-172 g SID CP/kg with either FM, SPC, SM or a combination
21
giving raise to two SM + SPC diets with different levels of SM and SPC. One week after
22
weaning, 96 pigs (body weight (BW) 9.6 ± 0.4 kg) were individually housed and allocated to one
23
of the four diets (n=24) and feed ad libitum for a 14-d period. Average daily feed intake (ADFI),
24
average daily gain (ADG) and gain to feed ratio (G:F) were determined. Pigs fed the SM10%
25
Manuscript to be submitted
25
diet had an ADG 23-28% lower (P<0.001) than pigs fed the FM, SPC and SM5% diets, despite
26
that they ate the same amount of feed. Faeces characteristics were evaluated by visual judgement
27
during five days and no differences were observed, indicting no effect of the diet on diarrhoea.
28
Blood samples were collected on d 15. Plasma urea nitrogen (PUN) in SM10% was higher
29
(P<0.003) than the concentrations in SPC and SM5% but not FM. Plasma Ca concentration was
30
higher (P<0.001) in pigs receiving SM10% compared to FM, SPC and SM5%. The opposite was
31
the case with P where the concentration was lower (P<0.001) in SM10% compared to FM, SPC
32
and SM5%. In conclusion, feeding diet SM5% resulted in performance equal to pigs fed the
33
control diets. Inclusion of 10% SM in the diet affects performance negatively, due to the wide
34
Ca:P in the SM10% diet that affects digestibility and absorption of P negatively. Moreover, the
35
possible formation of mineral-phytate complexes may reduce mineral bioavailability. The
36
negative effects increases as the dietary Ca:P increases. The determining factor for the maximum
37
inclusion level of SM in diets for piglets may be the dietary Ca level and the resulting Ca:P.
38
39
Keywords: Dietary protein source, nutrition, performance, piglets, starfish.
40
41
1. Introduction
42
The global demand for high-quality protein feedstuffs for use in animal nutrition is
43
increasing. Together with variability in the price development of agricultural commodities on the
44
world market along with the cost and availability of protein sources, the livestock production is
45
driven to explore alternative feedstuffs for animal nutrition in order to maintain the
46
competitiveness of livestock products (Trostle, 2008; Jezierny et al., 2010). Therefore, the
47
interest to maximise the use of sustainable and locally produced feed ingredients is increasing.
26
Manuscript to be submitted
48
Starfish in high concentrations is considered as pests by the commercial mussel farmers
49
because starfish predate mussels that are otherwise used for human consumption (Holtegaard et
50
al., 2008). Starfish meal (SM) is not a new product, and was evaluated as feed ingredient in
51
studies with poultry several decades ago. It was concluded that the protein fraction in SM was
52
comparable to fish meal (FM) in quality (Bird, 1946; Whitson and Titus, 1946; Levin et al.,
53
1960). However, the high calcium (Ca) content in SM was reported to result in poor growth
54
performance (Heuser and McGinnis, 1946; Morse et al., 1946; Whitson and Titus, 1946) and
55
reduce protein digestibility (Stutz and Matterson, 1964) when fed in high amounts to poultry.
56
The chemical composition and standardized ileal digestibility (SID) of crude protein (CP) and
57
amino acids (AA) in SM has been evaluated in pigs (Nørgaard et al., 2015), and their findings
58
showed chemical characteristics making SM potential for use in commercial diets for piglets.
59
Starfish show numerous chemical components that exhibit e.g. antimicrobial, antiviral and
60
antifungal activities (Dong et al., 2011) and can also of this reason be of great interest, if SM
61
shows any significant bioactivity effect on pig performance. This point toward a potential use of
62
SM in pig diets and as a serious competitor to well-known high-quality protein sources in
63
piglets, both due to its sustainability and local origin and nutrient composition. However, the use
64
of SM as feed ingredient in diets for pigs has not been reported. Based on this, it was
65
hypothesised, that feeding a diet containing SM will generate the same average daily feed intake
66
(ADFI), average daily gain (ADG) and gain to feed ratio (G:F) as traditional diets.
67
68
The objective of the present study was to evaluate whether piglets fed a diet containing SM
as a protein source perform on equal terms with pigs fed traditional diets for newly weaned pigs.
69
70
2. Materials and methods
27
Manuscript to be submitted
71
The experiment complied with the Danish Ministry of Justice, Act no. 253 of March 2013
72
concerning experiments with animals and care of experimental animals and a license issued by
73
the Danish Animal Experiments Inspectorate, the Ministry of Food, Agriculture and Fisheries,
74
Danish Veterinary and Food Administration.
75
76
2.1 Animals and diets
77
A total of 96 cross-bred (Danish Landrace/Yorkshire x Duroc) female and male castrated
78
pigs at the same proportion were included in the experiment. Seven days after weaning the pigs
79
were housed individually in pens (1.0 × 2.2 m) with visual and physical contact to neighbouring
80
pigs. The pens comprised two-thirds concrete floor and one-third cast iron slatted floor which
81
permitted drainage. The pigs were placed in three identical rooms of 16 pens, 4 from each
82
treatment per room. During the experimental period, room environment was controlled:
83
temperature 23°C, humidity 67% and the electrical light was on for 12 hours a day.
84
Starfish (Asterias rubens) were caught in Limfjorden in Denmark in October 2014 using a
85
specialized starfish purse serine. In two days, approximately 32 t of starfish was caught by three
86
36-45 feet boats at a speed of 1.5-2 knot. The starfish was transported from the harbour in
87
Nykøbing Mors to a fish meal plant (Hanstholm Fiskemelsfabrik, Denmark) where they were
88
processed into meal. The SM was prepared by mincing the starfish followed by drainage in the
89
drying facility under normal pressure in contiguity with rotating heat surfaces. The retention time
90
in the drying facility was 2-2½ hour depending on the moisture content. The meal reached a
91
temperature of approximately 100°C and a water content of 5-10% was achieved in the final
92
product. During the process, the water content was controlled every hour by using a dry matter
93
analyser. The dried starfish was grinded into meal by using a 10 mm griddle and sealed into big
94
bags.
28
Manuscript to be submitted
95
The pigs were allocated to one of four diets formulated to contain different protein sources;
96
fish meal (FM; FF classic, FF Skagen, Skagen, Denmark), soy protein concentrate (SPC;
97
AlphaSoy PIG 530, Agro Korn, Videbæk, Denmark) and two levels of starfish meal (SM;
98
starfish meal). The chemical composition of the main ingredients (Table 1) was determined
99
before the diets were optimized and diets were planned to be isoenergetic (9.4 MJ NE/kg as-fed)
100
and to fulfil the pigs minimum requirement for indispensable AA, Ca and P according to the
101
Danish recommendations for pigs weighing 9 to 15 kg (Tybirk et al., 2014). The composition
102
and, calculated and analysed chemical composition of the diets is presented in Table 2. All four
103
diets contained 174.4 g dehulled toasted soybean meal (SBM)/kg and were supplemented up to
104
166-172 g SID CP/kg with either FM, SPC, SM or a combination of these protein sources giving
105
raise to two SM + SPC diets with different levels of the two protein sources. Since all diets were
106
formulated to contain approximately 20% CP, SM as such, could not be fed as a sole source of
107
dietary protein besides SBM, without appreciably increasing the Ca level of the diet. Therefore,
108
SM was mixed with SPC, leading to a diet containing 5% SM (SM5%) and one containing10%
109
SM (SM10%). Diets were provided in meal form.
110
111
112
2.2 Experimental design
Pigs were weaned at day 25-32 of age. During the first week after weaning, the pigs were
113
fed a commercial diet containing 2500 ppm Zn. The experiment was conducted in two
114
periods/replicates with 48 pigs in each period, each with duration of two weeks. The experiment
115
started 7 days after weaning, i.e. without an adaption period, with an average initial body weight
116
(BW) of 9.6 ± 0.4 kg (9.3 ± 0.3 kg in period 1 and 9.8 ± 0.4 kg in period 2). The experimental
117
diet was designed to be a potential substitute for commercial diets for pigs with BW 9 to15 kg,
118
therefore, the experiment started one week after weaning. The pigs were allocated to one of four
29
Manuscript to be submitted
119
experimental diets and balanced according to sex, weight and room. The pigs were provided feed
120
ad libitum for 14 days. The feed was supplied twice daily to ensure fresh feed, with feed
121
dispensers adjusted on a regular basis to minimize feed spillage. Feed spillage was collected and
122
weighed daily and stored (4°C) for analysis of dry matter. The pigs had permanent access to
123
fresh water from drinking nipples.
124
Pigs were weighed on day 0, 7 and 14 of the experimental period. Average daily feed intake
125
and ADG were determined day 7 and 14. Faeces characteristics were evaluated during five
126
consecutive days from day 5 to 9 of the experiment by visual judgement in both periods. Faeces
127
were given one of four scores: 1, firm and shaped; 2, soft and shaped; 3, loose/often shining
128
surface, or 4, watery/flows through slatted floors (Pedersen and Toft, 2011). Piglets showing
129
score 4 for two consecutive days were treated for diarrhoea with injection of antibiotics
130
(Engemycin Vet, 100 mg/ml oxytetracyclin, MSD Animal Health, Ballerup, Denmark) for three
131
days as prescribed by the veterinarian. The pigs were monitored daily and the general health
132
status was recorded.
133
Blood samples were collected on day 15 of the first period of the experiment after an
134
overnight fasting starting at 1800 h. On the day of sampling, pigs received 25 g/kg BW0.75 of
135
feed at 0730 h. Blood samples were collected starting at 0930 h. The meal size and feeding time
136
before blood sampling was fixed to reduce variation. Blood samples were collected by jugular
137
vein puncture into 9 mL heparinized tubes (Greiner BioOne GmbH, Kremsmünster, Austria) and
138
immediately placed on ice. Samples were mixed and centrifuged at 2000 × g at 4°C for 10 min.
139
Plasma was immediately harvested and stored at -80°C until laboratory analysis.
140
141
2.3 Chemical analysis
30
Manuscript to be submitted
142
Dry matter content was determined for wheat, barley, SBM, FM, SPC, SM and feed
143
residuals by oven drying at 103°C for 20 hours. Nitrogen content for wheat, barley, SBM, FM,
144
SPC and SM was analysed by a modified Kjeldahl method (AOAC Int., 2000; 984.13), and CP
145
was estimated as total nitrogen × 6.25. Crude fat was extracted with petroleum ether after a
146
hydrochloric acid hydrolysis (European Commission, 2009; Procedure B). Representative
147
samples of each of the six before mentioned ingredients were hydrolysed for 23 hours at 110°C
148
with (Cys and Met) or without (Arg, His, Ile, Leu, Lys, Phe, Tyr, Thr, Trp, Val) performic acid
149
oxidation, and AA were separated by ion exchange chromatography and quantified by
150
photometric detection after ninhydrin reaction (European Commission, 1998).
151
Blood plasma were analysed for plasma urea nitrogen (PUN), AA, Ca and inorganic P.
152
Blood plasma free AA and PUN were analysed using an Amino Acid Analyser fitted to a lithium
153
high performance system for physiological amino acids (Biochrome 30+ Amino Acid Analyser;
154
Biochrome, Cambridge, England). The Amino Acid Analyser was calibrated using a standard for
155
acidic, neutral, and basic AA (Sigma Aldrich, St. Louis, MO). Calcium and inorganic P (plasma
156
only) concentrations were measured photometrically on a Roche/cobas c 111 analyser (Roche
157
Diagnostics International Ltd., Rotkreuz, Switzerland) using commercial reagents (Roche
158
Diagnostics GmbH, Mannheim, Germany). The analyser was calibrated using a lyophilized
159
human serum (Roche Diagnostics GmbH, Mannheim, Germany) as well as 0.9% NaCl.
160
Precinorm U and Precipath U based on lyophilized human serum (Roche Diagnostics GmbH,
161
Mannheim, Germany) were used as controls.
162
163
164
165
2.4 Calculations and statistical analyses
Gain to feed ratio was calculated by ADG divided by ADFI. All statistical processes were
performed in SAS (Version 9.3, SAS Inst. Inc., Cary, NC, US), using the individual pig as
31
Manuscript to be submitted
166
experimental unit. Animal performance data (ADFI, ADG and G:F) and plasma AA, Ca,
167
inorganic P and PUN were analysed by the MIXED procedure (Littell et al., 2002), as all
168
variables showed normal distribution by histogram plots. The models all included diet (diet 1 to
169
4) and sex (female, castrate) as fixed effects, and initial BW as a covariate. Room (room 1 to 3)
170
and period (1, 2; rooms were used twice) were handled as random variables, though period was
171
not included in the models for plasma parameters, since blood samples were only taken by the
172
end of the first period. All models have been tested for three-way and two-way interactions, but
173
the interactions were not significant for any of the response variables and were left out of the
174
final models.
175
Faeces score data are presented as the distribution of scores during the evaluation period
176
from day 5 to 9 in both periods. The distribution of days on the four faeces scores were analysed
177
using the GLIMMIX procedure (Littell et al., 2002) with a multinomial distribution (a
178
generalization of the binomial distribution) and a cumulative logit link function (i.e. the response
179
was restricted to one of a finite number of ordinal values). The model included diet (diet 1 to 4),
180
score day (d 5 to 9), the interaction term diet × score day, and the initial weight as covariate.
181
Room was handled as random effect.
182
Applied to all models, residual variance has been examined by plotting the residuals against
183
the predicted values. Applicable for all the models, the residuals were evenly distributed around
184
zero, and the models were therefore accepted. Presented data are least squares means and
185
standard error of mean (SEM). Statistically significance was accepted at P<0.05.
186
187
3. Results
188
3.1 Chemical composition of the protein sources and diets
32
Manuscript to be submitted
189
The SM was characterized by containing half the CP/kg DM of FM, and more than double
190
the ash content. The protein fraction of SBM, FM, SPC and SM was analysed for 11 AA, and
191
difference was found between the content. However, the content of the individual AA in relation
192
to CP, i.e. the AA profile, was similar among the protein sources. Starfish meal was lower in
193
Trp, Phe and His compared to the other protein sources. Starfish meal was comparable to FM in
194
AA composition, but had a higher content of Met and Cys. Soybean meal and SPC were very
195
similar in their composition of AA, but the content of Met was only about half of the content in
196
SM and FM. The SM was analysed for sand (acid-insoluble ash) to explain the high ash content
197
(data not shown), but the content was negligible. Approximately one third of the ash content in
198
SM consisted of Ca (130 g/kg DM) and the content of P was 63 g/kg DM.
199
The calculated chemical composition of the FM, SPC and SM5% diets were similar between
200
treatment, whereas the SM10% diet had a higher CP, ash, fat, Ca and Na content, compared to
201
the other diets. The analysed values for CP were more similar among diets, and in general, the
202
analysed values were higher than the calculated. The Ca:P was in the range of 1.5:1 to 2.6:1,
203
where SPC and SM5% had the narrowest and SM10% had the widest ratio.
204
205
3.2 Animal performance, faeces score and plasma samples
206
In general, pigs maintained good health status during the experiment. Average daily feed
207
intake, ADG and G:F performance of animals divided in d 1-7, d 7-14 and d 1-14 are given in
208
Table 3. Average daily feed intake did not differ significant among diets in either one of the
209
periods. No significant differences of diet on ADG and G:F were observed among pigs fed FM,
210
SPC and SM5% in any of the periods. In all periods, pigs receiving SM10% had lower (P<0.001)
211
ADG and G:F compared to FM, SPC and SM5%. From d 1 to 14, pigs fed the SM10% diet had
33
Manuscript to be submitted
212
an ADG, which was 23-28% lower (P < 0.001) than pigs fed the FM, SPC and SM5% diets,
213
despite that they ate the same amount of feed.
214
215
Faeces characteristics were evaluated from day 5 to 9 in both periods. The data from the
evaluation periods, showed no significant differences among diets (Table 4).
216
There was no significant difference in PUN concentration between pigs fed diet FM, SPC
217
and SM5%, but the concentration of PUN was higher (P<0.003) for SM10% compared with the
218
plasma concentration in SPC and SM5%, but not FM (Table 5). Plasma concentration of Thr in
219
SPC was higher (P<0.001) than the plasma concentration in SM5% and SM10%, but not FM.
220
The Met concentration in plasma from pigs fed SPC was higher (P<0.003) than in plasma from
221
FM and SM10%, but not SM5%. Regarding Ca, there was a higher (P<0.001) concentration of
222
Ca in plasma from pigs receiving SM10% compared to FM, SPC and SM5%. The opposite was
223
the case with P where the concentration was lower (P<0.001) in SM10% compared to FM, SPC
224
and SM5%.
225
226
4. Discussion
227
Data from the present study supported the hypothesis that feeding a diet containing SM to
228
piglets from BW 7 to 15 kg, will give the same ADFI, ADG and G:F as diets containing
229
traditional protein sources. This was, however, only the case when the inclusion level of starfish
230
meal was 5% and not 10%. Despite it has been concluded that the protein fraction in SM is
231
comparable to that of FM in quality (Bird, 1946; Whitson and Titus, 1946; Levin et al., 1960),
232
the poor growth results obtained on high amounts of SM in studies with poultry, was suggested
233
to be caused by the excess dietary Ca, which also widened the Ca:P of the diet (Heuser and
234
McGinnis, 1946; Morse et al., 1946; Whitson and Titus, 1946). In the present experiment, pigs
235
offered the diet containing 10% SM with a Ca:P of 2.6:1 (14.8 g Ca and 5.8 g P per kg feed)
34
Manuscript to be submitted
236
(Table 2) had no detrimental effect on ADFI, but ADG and G:F were lower than in pigs offered
237
diets containing FM, SPC and SM5%. The dietary Ca and P levels in the SM10% diet was above
238
the Danish recommendations (Tybirk et al., 2014) for pigs with BW of 9 to 15 kg (8.7 g Ca and
239
5.7 g total P per kg feed when phytase is added). Due to the design of the experiment, to see the
240
response of different levels of SM in pigs, it was necessary to have a level of Ca higher than
241
recommended.
242
Phosphorus has been shown to exert greater influence on growth characteristics than Ca
243
(Maxson and Mahan, 1983) as P plays a major role in the development and maintenance of the
244
skeletal system and is also involved in muscle tissue deposition (Varley et al., 2011). In the
245
SM10% diet, there could be a possible interaction among the feed ingredients. Starfish do not
246
contain phytate, but plant ingredients contain phytic acid. Digestion and utilization of dietary
247
phytate-P by monogastric animals requires hydrolysis of phytate by phytase (Fisher, 1992). The
248
apparent negative impact of high Ca level and wide Ca:P, when feeding the SM10% diet on
249
ADG and G:F, may be a detrimental effect on phytase activity. The negative effects of extra Ca
250
in the diet on the efficacy of phytase, may be explained by three mechanisms: 1) High Ca level
251
may lower P absorption as a result of the formation of insoluble phytate-Ca complexes in the
252
small intestine that is not accessible for hydrolysis by phytase (Wise, 1983; Fisher, 1992), 2)
253
high Ca levels increases the pH of the intestinal content, which decrease the exogenous phytase
254
activity (Sandberg et al., 1993) and 3) high Ca levels in the diet may directly reduce the activity
255
of the phytase by competing for the active sites of the enzyme, limiting phytase efficacy in
256
hydrolysing phytate-P (Wise, 1983; Qian et al., 1996). In the SM10% diet there was a high
257
dietary Ca level, and it is found that increasing the dietary Ca level, decreases the apparent totalt
258
tract digetibility (ATTD) of P in a phytase-supplemented diet (Liu et al., 1998). This was
259
confirmed by Qian et al. (1996), who found that reducing the Ca:P from 2.0:1 to 1.2:1 increased
35
Manuscript to be submitted
260
phytase efficiency by approximately 16% and at the same time improved performance.
261
Moreover, Lei et al. (1994) demonstrated that the ability of phytate to improve phytate-P
262
availability was greatly reduced when widening the Ca:P from 1.3:1 (4.8 g Ca/kg, 3.2 g P/kg) to
263
3.0:1 (8.8 g Ca/kg, 2.9 g P/kg). The high Ca level in the SM10% diet may, therefore, may have
264
inhibited phytase activity and lowered the ATTD of P, hence, the level of P to maximize muscle
265
tissue deposition may have been insufficient (Varley et al., 2011). The effect of the wide Ca:P in
266
the SM10% diet is substantiated by the plasma concentrations of Ca and P (Table 5), which
267
showed higher Ca level and lower P level compared to pigs fed the other diets. As Ca:P is
268
increased, an inverse relationship of serum Ca and P has been reported, where serum Ca linearly
269
increases and serum inorganic P decreases. This substantiate that the digestibility and absorption
270
of P decreases as the dietary Ca:P increases. That is, increased dietary Ca levels results in
271
decreased ATTD of P (Stein et al., 2011). Furthermore, divalent minerals can readily bind to
272
phytic acid and thus form mineral-phytate complexes that may be resistant to hydrolysis by
273
phytase. Formation of these complexes is associated with a reduction in mineral bioavailability
274
(Maenz et al., 1999). Mineral-phytate complexes are mainly formed at a pH that is above, or the
275
upper limit of the microbial phytase activity spectrum (Selle et al., 2000). Thus, the pH in the gut
276
may have an influence on the efficiency of phytase, where the high Ca level most likely create a
277
buffering effect thereby increasing pH (Stein, 2002). Hence, availability of both P and minerals
278
involved in growth performance can be reduced by high Ca levels.
279
Pigs receiving diet SM10% had same ADFI as did pigs on the other diets. A palatability
280
study done by Falkowski et al. (1998) found that pigs preferred a high NaCl content (0.57%) in
281
the diet. Palatability may have driven the pigs to eat more of the SM10% diet containing a higher
282
level of Na (Table 2), therefore having the same ADFI as the other diets. But the lower ADG of
283
pigs fed the SM10% diet indicates that the pigs have not been capable of utilizing the consumed
36
Manuscript to be submitted
284
feed. Dietary NaCl enhance P absorption and improve its digestibility due to the active transport
285
of P from the intestinal lumen via the Na+/Pi co-transport (Yin et al., 2008). Furthermore, Na
286
plays a role in the intestinal absorption of AA. The missing apparent power of Na, can be a result
287
of the wide Ca:P as discussed above.
288
Plasma urea nitrogen is an indicator of AA catabolism and the concentration can be related
289
to protein requirement, an unbalance in the AA profile and/or over supply of protein (Zervas and
290
Zijlstra, 2002). Since the four diets only slightly differed in CP level (Table 2) and were
291
optimised to have the same content of SID AA (Table 2), the higher PUN concentration found in
292
the SM10% diet, indicates that the requirement for CP was met at or before the CP content of the
293
SM10% diet. No explanation was found for the significant differences observed in both Thr and
294
Met concentration in plasma (Table 5) in the experiment.
295
The registration of faeces characteristics indicated no diet dependent effect on the incidence
296
of diarrhoea, and in general the incidence of diarrhoea was low. One of the reasons may be the
297
seven days pre-experimental period from weaning to the beginning of the experiment. This
298
period was included to secure that all pigs ate from the beginning of the experimental period and
299
thus had been adapted to the shift from sow milk to dry feed. Another reason could be that the
300
diets contained only 166-172 g SID CP/kg, which is lower than the diets reported to cause
301
diarrhoea. Diets formulated to less than 180 g CP/kg and fortified with crystalline AA to supply
302
adequate indispensable AA levels for growth, can minimise the expression of diarrhoea (Heo et
303
al., 2009; Kim et al., 2012). High levels of dietary Ca can create a buffering effect in the
304
digestive tract, which can cause diarrhoea in piglets (Stein, 2002). However, no increase in
305
faecal score was observed in pigs fed SM10% diet.
306
307
The chemical composition of SM is promising in relation to pig feed, but the literature
shows variable level of CP varying from 27-36% (Levin et al., 1960), 34% (Bird, 1946;
37
Manuscript to be submitted
308
Ringrose, 1946) to 70% (Nørgaard et al., 2015). Levin et al. (1960) found indication of that all
309
the constituents of starfish are variable and depends largely on size, freshness, season and
310
environmental factors associated with the specific samples. The knowledge of the biochemical
311
composition of the starfish tells when it is most favourable to fish them. It was reported by
312
Oudejans and Vandersluis (1979) that during the year, the total AA content and relative
313
distribution of AA in proportion to CP is rather constant, while the content of CP varies; lowest
314
in June until autumn and greatest in May following the starfish reproduction cycle. Fishing
315
starfish in May, which was the case in the study by Nørgaard et al. (2015), will in relation to
316
using starfish as a feed ingredient for pigs be of greatest interest. In the present study the starfish
317
was caught in November, amounting a CP level of 38%.
318
319
5. Conclusion
320
Inclusion of 5% SM in the diet for piglets with BW 9-15 kg resulted in pig performance equal to
321
diets containing either FM or SPC. Starfish meal is therefore a potential competitor to high-
322
quality protein sources for piglets. Pigs fed 10% SM had lower ADG and G:F than pigs fed the
323
other diets, but results on ADFI was not significantly different among treatments. The negative
324
effect on performance when feeding the SM10% diet, may be the high Ca level and wide Ca:P
325
that affects digestibility and absorption of P negatively. Moreover, binding of divalent minerals
326
to phytic acid and thus formation of mineral-phytate complexes, may reduce mineral
327
bioavailability. The negative effects increases as the dietary Ca:P increases. The determining
328
factor for the maximum inclusion level of SM in diets for piglets may be the dietary Ca level and
329
the resulting Ca:P.
330
331
Conflict of interest statement
38
Manuscript to be submitted
332
The author has no conflict of interest regarding this work.
333
334
Acknowledgements
335
The research project was founded by the Green Development and Demonstration
336
Programme under the Ministry of Food, Agriculture and Fisheries, Denmark, grant number
337
34009-14-0845.
338
339
References
340
AOAC Int., A., 2000. Official Methods of Analysis of AOAC International, Method 984.13.
341
17th ed. Journal of AOAC International, Gaithersburg, MD.
342
Bird, H.R., 1946. Dehydrated pea vines and starfish meal in poultry feeds, Studies on the marine
343
resources of sourthern New England. III the possibility of the utilization of starfish (Asterias
344
forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody
345
Museum of Natural History Yale University. Bingham Oceanographic Laboratory, New
346
Haven, Conn., U.S.A.
347
348
349
Dong, G., Xu, T.H., Yang, B., Lin, X.P., Zhou, X.F., Yang, X.W., Liu, Y.H., 2011. Chemical
Constituents and Bioactivities of Starfish. Chem. Biodivers. 8, 740-791.
European Commission, 1998. Commission Directive 98/64/EC of 3 September 1998 establishing
350
Community methods of analysis for the determination of amino-acids, crude oils and fats,
351
and olaquindox in feedingstuffs and amending Directive 71/393/EEC Official Journal of the
352
European Communities Eur-Lex - 31998L0064.
353
European Commission, 2009. Commission Regulation (EC) No 152/2009. Annex III Methods of
354
analysis to control the composition of feed materials and compound feed. Official Journal of
355
the European Communities Eur-Lex - 32011R0619.
39
Manuscript to be submitted
356
Falkowski, J., Kozera, W., Bugnacka, D., 1998. Effect of different fodder salt (NaCl) content of
357
diets on feed preferences of weaned pigs. Natural Sciences (formerly: Acta Academiae
358
Agriculturae ac Technicae Olstenensis).
359
Fisher, H., 1992. LOW-CALCIUM DIETS ENHANCE PHYTATE-PHOSPHORUS
360
361
AVAILABILITY. Nutrition Reviews 50, 170-171.
Heo, J.M., Kim, J.C., Hansen, C.F., Mullan, B.P., Hampson, D.J., Pluske, J.R., 2009. Feeding a
362
diet with decreased protein content reduces indices of protein fermentation and the incidence
363
of postweaning diarrhea in weaned pigs challenged with an enterotoxigenic strain of
364
Escherichia coli. Journal of Animal Science 87, 2833-2843.
365
Heuser, G.F., McGinnis, J., 1946. Starfish meal in chick rations, Studies on the marine resources
366
of sourthern New England. III the possibility of the utilization of starfish (Asterias forbesi
367
desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody Museum of
368
Natural History Yale University. Bingham Oceanographic Laboratory, New Haven, Conn.,
369
U.S.A.
370
Holtegaard, L.E., Gramkow, M., Petersen, J.K., Dolmer, P., 2008. Biofouling og Skadevoldere:
371
372
Søstjerner, Dansk Skaldyrscenter. Available at: http://www.skaldyrscenter.dk.
Jezierny, D., Mosenthin, R., Bauer, E., 2010. The use of grain legumes as a protein source in pig
373
374
nutrition: A review. Animal Feed Science and Technology 157, 111-128.
Kim, J.C., Hansen, C.F., Mullan, B.P., Pluske, J.R., 2012. Nutrition and pathology of weaner
375
pigs: Nutritional strategies to support barrier function in the gastrointestinal tract. Animal
376
Feed Science and Technology 173, 3-16.
377
Lei, X.G., Ku, P.K., Miller, E.R., Yokoyama, M.T., Ullrey, D.E., 1994. CALCIUM LEVEL
378
AFFECTS THE EFFICACY OF SUPPLEMENTAL MICROBIAL PHYTASE IN CORN-
379
SOYBEAN MEAL DIETS OF WEANLING PIGS. Journal of Animal Science 72, 139-143.
40
Manuscript to be submitted
380
Levin, E., Rand, N.T., Mosser, J.D., Varner, D.S., Collins, V.K., 1960. DEFATTED STARFISH
381
MEAL AS SOURCE OF NUTRIENTS IN POULTRY RATIONS. Poultry Science 39, 646-
382
654.
383
Littell, R.C., Stroup, W.W., Freud, R.J., 2002. SAS for linear models. SAS Institute, Cary, NC.
384
Liu, J., Bollinger, D.W., Ledoux, D.R., Veum, T.L., 1998. Lowering the dietary calcium to total
385
phosphorus ratio increases phosphorus utilization in low-phosphorus corn-soybean meal
386
diets supplemented with microbial phytase for growing-finishing pigs. Journal of Animal
387
Science 76, 808-813.
388
Maenz, D.D., Engele-Schaan, C.M., Newkirk, R.W., Classen, H.L., 1999. The effect of minerals
389
and mineral chelators on the formation of phytase-resistant and phytase-susceptible forms of
390
phytic acid in solution and in a slurry of canola meal. Animal Feed Science and Technology
391
81, 177-192.
392
Maxson, P.F., Mahan, D.C., 1983. DIETARY CALCIUM AND PHOSPHORUS LEVELS FOR
393
GROWING SWINE FROM 18 TO 57 KILOGRAMS BODY-WEIGHT. Journal of Animal
394
Science 56, 1124-1134.
395
Morse, R.E., Griffiths, F.P., Parkhurst, R.T., 1946. Preliminary report on eight weeks of
396
comparative feeding of protein equivalent diets containing fish meal, crab meal, and starfish
397
to Rhode Island red chicks, Studies on the marine resources of sourthern New England. III
398
the possibility of the utilization of starfish (Asterias forbesi desor), Bulletin of the Bingham
399
Bingham Oceanographic collection. Peabody Museum of Natural History Yale University.
400
Bingham Oceanographic Laboratory, New Haven, Conn., U.S.A.
401
Nørgaard, J.V., Petersen, J.K., Tørring, D.B., Jørgensen, H., Lærke, H.N., 2015. Chemical
402
composition and standardized ileal digestibility of protein and amino acids from blue
403
mussel, starfish, and fish silage in pigs. Animal Feed Science and Technology 205, 90-97.
41
Manuscript to be submitted
404
Oudejans, R., Vandersluis, I., 1979. CHANGES IN THE BIOCHEMICAL COMPOSITION OF
405
THE OVARIES OF THE SEASTAR ASTERIAS-RUBENS DURING ITS ANNUAL
406
REPRODUCTIVE-CYCLE. Mar. Biol. 50, 255-261.
407
Pedersen, K.S., Toft, N., 2011. Intra- and inter-observer agreement when using a descriptive
408
classification scale for clinical assessment of faecal consistency in growing pigs. Preventive
409
Veterinary Medicine 98, 288-291.
410
Qian, H., Kornegay, E.T., Conner, D.E., 1996. Adverse effect of wide calcium:phosphorus ratios
411
on supplemental phytase efficacy for weanling pigs fed two dietary phosphorus levels.
412
Journal of Animal Science 74, 1288-1297.
413
Ringrose, R.C., 1946. Starfish meal feeding experiment with chicks, Studies on the marine
414
resources of sourthern New England. III the possibility of the utilization of starfish (Asterias
415
forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody
416
Museum of Natural History Yale University. Bingham Oceanographic Laboratory, New
417
Haven, Conn., U.S.A.
418
Sandberg, A.S., Larsen, T., Sandstrom, B., 1993. HIGH DIETARY CALCIUM LEVEL
419
DECREASES COLONIC PHYTATE DEGRADATION IN PIGS FED A RAPESEED
420
DIET. Journal of Nutrition 123, 559-566.
421
Selle, P.H., Ravindran, V., Caldwell, R.A., Bryden, W.L., 2000. Phytate and phytase:
422
423
consequences for protein utilisation. Nutrition Research Reviews 13, 255-278.
Stein, H.H., 2002. Experience of feeding pigs without antibiotics: A European perspective.
424
425
Animal Biotechnology 13, 85-95.
Stein, H.H., Adeola, O., Cromwell, G.L., Kim, S.W., Mahan, D.C., Miller, P.S., Swine,
426
N.C.C.C., 2011. Concentration of dietary calcium supplied by calcium carbonate does not
42
Manuscript to be submitted
427
affect the apparent total tract digestibility of calcium, but decreases digestibility of
428
phosphorus by growing pigs. Journal of Animal Science 89, 2139-2144.
429
Stutz, M.W., Matterson, L.D.S., 1964. METABOLIZABLE ENERGY VALUES +
430
COEFFICIENTS OF DIGESTIBILITY FOR PROTEIN + FAT OF STARFISH MEAL +
431
STARFISH MEAL COMBINED WITH FISH MEAL. Poultry Science 43, 474-&.
432
Trostle, R., 2008. Global agricultural supply and demand: Factors contributing to the recent
433
increase in food commodity prices. A Report from the Economic Research Service, United
434
States Department of Agriculture Economic Research Service, Washington, DC. Retrieved
435
on 27 April 2015 from http://www.ers.usda.gov/media/218027/wrs0801_1_.pdf.
436
Tybirk, P., Sloth, N.M., Jørgensen, L., 2014. Nutrient Requirement Standards. 19th edition of the
437
Danish nutrient standards. Revised 24 April 2014. , Pig Research Centre, Copenhagen,
438
Denmark. Retrieved on 12 February 2015 from
439
http://www.pigresearchcentre.dk/About%20us/Nutrient%20standards.aspx.
440
Varley, P.F., Callan, J.J., O'Doherty, J.V., 2011. Effect of dietary phosphorus and calcium level
441
and phytase addition on performance, bone parameters, apparent nutrient digestibility,
442
mineral and nitrogen utilization of weaner pigs and the subsequent effect on finisher pig
443
bone parameters. Animal Feed Science and Technology 165, 201-209.
444
Whitson, D., Titus, H.W., 1946. The use of starfish meal in chick diets, Studies on the marine
445
resources of sourthern New England. III the possibility of the utilization of starfish (Asterias
446
forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody
447
Museum of Natural History Yale University. Bingham Oceanographic Laboratory, New
448
Haven, Conn., U.S.A.
449
450
Wise, A., 1983. Dietary factors determining the biological activities of phytate. Nutrition
Research Reviews 53, 791-806.
43
Manuscript to be submitted
451
Yin, Y.I., Huang, C.H., Wu, X., Li, T.J., Huang, R.L., Kang, P., Hu, Q., Chu, W.Y., Kong, X.F.,
452
2008. Nutrient digestibility response to graded dietary levels of sodium chloride in weanling
453
pigs. Journal of the Science of Food and Agriculture 88, 940-944.
454
Zervas, S., Zijlstra, R.T., 2002. Effects of dietary protein and oathull fiber on nitrogen excretion
455
patterns and postprandial plasma urea profiles in grower pigs. Journal of Animal Science 80,
456
3238-3246.
457
458
44
Manuscript to be submitted
459
Table 1
460
Analysed chemical composition (g/kg DM) of wheat, barley, dehulled toasted soy bean meal
461
(SBM), fish meal (FM), soy protein concentrate (SPC) and starfish meal (SM).
Item
Wheat
Barley
SBM
FM
SPC
SM
Dry matter
886
898
909
950
916
961
Crude protein (CP)
108
118
496
735
552
383
Crude ash
17
21
76
171
71
421
Crude fat
22
29
19
90
30
91
Ca
0.29
0.28
3.0
36
3.4
130
P
3.0
3.3
7.5
24
7.2
63
Cys
2.3
2.6
7.6
6.5
8.0
4.7
His
2.4
2.5
13.3
14.4
14.0
6.1
Ile
3.6
4.3
24.1
32.0
27.6
14.5
Leu
6.8
7.8
38.0
52.8
42.8
21.4
Lys
3.1
4.2
30.7
56.2
32.5
20.6
Met
1.6
1.9
6.7
20.7
7.2
8.1
Phe
4.7
5.6
25.7
28.4
29.2
12.5
Thr
3.0
3.8
19.9
29.8
21.6
18.0
Trp
1.3
1.4
6.8
7.3
7.1
3.8
Val
4.7
6.1
25.4
37.0
27.8
17.8
462
463
45
Manuscript to be submitted
464
Table 2
465
Composition, and calculated and analysed chemical composition (g/kg, as-fed basis) of
466
experimental diets containing fish meal (FM), soy protein concentrate (SPC) and 5 or 10%
467
starfish meal (SM).
FM
SPC
SM5%
SM10%
Wheat
536
504
500
469
Barley
200
200
200
200
SBM
174
174
174
174
SM
-
-
50
100
SPCa
-
75
52
33
FMb
55
-
-
-
Calcium carbonate
17.2
15.6
9.1
-
Mono-calcium phosphate
5.6
9.9
9.1
8.4
Soy oil
-
6.0
1.4
4.0
NaCl
2.3
3.6
1.8
-
Vitamin-mineral premixc
4.0
4.0
4.0
4.0
L-Lysin HCl (780 g/kg)
3.5
4.4
4.2
3.9
DL-Methionine (990 g/kg)
0.8
1.4
1.2
1.0
L-Threonine (985 g/kg)
1.2
1.4
1.1
0.8
L-Tryptophan (980 g/kg)
0.3
0.2
0.2
0.2
Microgritsd
0.5
0.5
0.5
0.5
Phytase (Natuphos 5000)e
0.2
0.2
0.2
0.2
Ingredient
Calculated chemical composition
46
Manuscript to be submitted
Dry matter
865
853
877
881
Crude ash
60.8
60.5
61.2
77.2
Crude fat
23.3
26.0
25.0
30.9
Crude protein (CP)
194
192
198
203
SID CPf
167
166
170
172
SID lys
11.4
11.4
11.4
11.4
Ca
10.2
8.7
8.7
14.8
P
5.7
5.9
5.8
5.8
Ca:P
1.8:1 1.5:1 1.5:1
2.6:1
Na
1.6
1.6
2.2
2.8
Dry matter
903
903
902
903
Crude ash
63.9
58.9
65.0
80.3
Crude fat
26.9
28.0
30.0
34.9
CP
206
202
204
207
Analysed chemical composition
468
a
AlphaSoy PIG 530 (Agro Korn, Videbæk, Denmark).
469
b
FF classic (FF Skagen, Skagen, Denmark).
470
c
Danish Vilomix A/S. Provided per kg diet: 11,000 IU vitamin A, 1,000 IU vitamin D3, 16.9 IU
471
vitamin E, 4.4 mg vitamin K3, 4.4 mg vitamin B1, 8.8 mg vitamin B2, 6.6 mg vitamin B6, 0.04
472
mg vitamin B12, 22 mg Ca-D-panthotenic acid, 44 mg niacin, 0.44 mg biotin, 330 mg Fe (FE (II)
473
sulphate), 260 mg Cu (Cu (II) sulphate), 200 mg Zn (Zn oxide), 88 mg Mn (Mn oxide), 0.44 mg
474
I (calciumjodat), and 0.50 mg Se (natriumselenite).
475
d
Jadis Additiva (Haarlem, NL). Corn bran in various colours to identify diets.
476
e
Natuphos 5000 (BASF, Ludwigshafen, Germany).
47
Manuscript to be submitted
477
f
SID, standardised ileal digestible.
48
Manuscript to be submitted
478
Table 3
479
Average daily feed intake (ADFI), average daily gain (ADG) and gain to feed ratio (G:F) of pigs
480
fed diets containing fish meal (FM), soy protein concentrate (SPC) and 5 or 10% starfish meal
481
(SM).1
Item
FM
SPC
SM5%
SM10%
SEM
P-value
ADFI, g, d 1-7
717
681
705
647
25
0.06
ADG, g, d 1-7
593a
557a
591a
438b
22
<0.001
G:F, d 1-7
0.829a
0.832a
0.843a
0.667b
0.04
<0.001
ADFI, g, d 7-14
1023
997
1064
1066
36
0.25
ADG, g, d 7-14
756a
736a
744a
615b
33
<0.001
G:F, d 7-14
0.738a
0.744a
0.701a
0.579b
0.02
<0.001
ADFI, g, d 1-14
861
836
884
862
31
0.55
ADG, g, d 1-14
675a
650a
669a
526b
20
<0.001
G:F, d 1-14
0.770a
0.774a
0.760a
0.614b
0.01
<0.001
482
a,b
483
1
Means within rows without a common superscript differ (P≤0.05).
Values are least squares means and standard errors of the means (SEM). n = 24.
484
49
Manuscript to be submitted
485
Table 4
486
Distribution of faeces scores of pigs fed diets containing fish meal (FM), soy protein concentrate
487
(SPC) and 5 or 10% starfish meal (SM).1
FM
SPC
SM5%
SM10%
P-value2
Score 1
26
34
19
25
0.47
Score 2
51
40
47
50
Score 3
39
43
44
37
Score 4
4
3
5
8
488
1
489
watery/flows through slatted floors.
490
2
491
the diets.
Faeces score: 1, firm and shaped; 2, soft and shaped; 3, loose/often shining surface, or 4,
The P-value is based on a F-test for differences in the distribution of days with score 1-4 among
492
50
Manuscript to be submitted
493
Table 5
494
Plasma urea nitrogen (PUN) and amino acid concentrations (µmol/L), and calcium and
495
phosphorus plasma concentrations (mg/L) in pigs 120 minutes after feeding 25 g diet/kg BW0.75
496
on day 15 in period 1 after an overnight fasting. The experimental diets containing either fish
497
meal (FM), soy protein concentrate (SPC) and 5 or 10% starfish meal (SM).1
Item
FM
SPC
SM5%
SM10%
SEM
P-value
PUN
3254ab
2594b
2914b
3919a
246
0.003
Ile
127
158
141
126
23
0.23
Leu
141
167
147
130
23
0.18
Lys
238
276
224
220
36
0.22
Met
42b
61a
56ab
41b
7
0.003
Phe
82
99
88
82
14
0.15
Thr
154ab
203a
145b
105b
25
<0.001
Trp
44
48
43
45
7
0.88
Tyr
90
115
100
88
15
0.07
Val
222
240
226
227
33
0.86
Ca
113b
114b
114b
128a
1
<0.001
P
100a
103a
103a
72b
2
<0.001
498
a,b
499
1
Means within rows without a common superscript differ (P≤0.05).
Values are least squares means and standard errors of the means (SEM). n = 12.
51
52
General discussion of results and the study
GENERAL DISCUSSION OF RESULTS AND THE STUDY
6
Discussion and future development
This section of the thesis will discuss the results in general and the methods of the study. It will be
discussed whether the study could have been improved, and if so, how. Moreover, supplementary
results on FA composition of SM left out of the manuscript will be presented and discussed, and
finally, the possibility of further development of SM. Discussion in manuscript will not be repeated.
6.1 Design of the study
It was determined beforehand that the piglets should be individually housed, but the remaining
elements of the study were yet to be chosen. These elements included the target group of the
experimental diets, number and composition of the diets, number of piglets necessary to have
enough repetitions per diet, parameters to be measured and the whole procedure during the study.
When choosing the number and composition of the experimental diets, simple diets with few
ingredients were composed, which is seldom the case with diets for the specific target group. They
often contain a number of different high-quality protein sources. The purpose was to make diets that
more clearly identified what affected piglet performance, and relatively be able to rule out any
affecting interactions among the feed ingredients. It was a difficulty to balance a diet containing
10% SM, according to the recommendations especially regarding Ca. The content of Ca is high in
SM (Stutz and Matterson, 1964; Nørgaard et al., 2015), hence, the maximum level of Ca in the diet
is met rapidly, by which the possible inclusion level of SM was limited. Consequently, that
precluded the possibility to fulfil the need for the other nutrients such as AA requirements. Well
aware that the high Ca level in the SM10% diet could negatively affect performance in pigs, since it
has been reported in poultry (Heuser and McGinnis, 1946; Ringrose, 1946; Stutz and Matterson,
1964), it was more relevant to see the result of a higher level of SM included in the diet than
possible, if to follow the nutrient recommendations. This was due to several reasons, both that
performance studies with SM and pigs have never been conducted, and also the possibility to see
differences in performance, if any, among the diets. The study was intended to be on performance
in relation to SM, and the most important measures were found to be feed intake, weight gain,
faeces characteristics and blood parameters. Another parameter brought into play was having the
pigs in metabolism cages and collect faeces and urine. If the Ca:P is greater than that needed for
bone tissue synthesis, excretion of Ca in the urine is increased due to low availability of P
53
General discussion of results and the study
(Gonzalez-Vega and Stein, 2014). Moreover, calculation of absorption and retention of both Ca and
P would be possible giving an indication of the availability of the two minerals (Gonzalez-Vega et
al., 2013). Dissection was also brought into play to evaluate bone composition. The activity of cells
involved in bone tissue degradation and synthesis is regulated by parathyroid hormone and
calcitonin, in which the secretion of these hormones is dependent on the concentration of Ca in
plasma (Gonzalez-Vega and Stein, 2014). When concentrations of Ca in plasma are lower than
normal, parathyroid hormone is secreted, resulting in increased resorption of Ca from bones. The
results from the study conducted by Reinhart and Mahan (1986) suggested that high Ca:P can
adversely affect bone development, including percent bone ash, bone wall thickness and bonebending moment. Hence, urine, faeces and bone tissue could contribute in explaining the results
observed. This was, however, more than the budget could handle, and moreover, would be too farreaching in relation to the objective of the study.
A neglected factor in the study was the relative high content of Na in the SM10% diet. It could have
been interesting to record the water consumption, since many of the pigs receiving diet SM10%
“moved” water from the drinking nipple to the container, making the feed wet. Pigs can tolerate
high levels of NaCl (Todd et al., 1964; Mason and Scott, 1974; Chittavong et al., 2013), provided
that water is freely available. However, no indication of a negative effect of NaCl content was
found. Furthermore, it would have been interesting to record the water consumption, if there were
any difference among piglets.
6.2 Faeces score method
A study with observations requires a test for intra-observer reliability to be done to make sure that
the observations also resemble each other throughout the entire period. Faeces characteristics are
highly subjective measurements and what is observed can be very different from person to person.
To ensure that the observations in the first period of the study resembled the observations obtained
in the second period, pictures of the different scores of faeces were taken in the first period to have
something to resemble the second period. Normally, resembling can be done by making some of the
early observations later in the period and comparing the result. This was not possible in this case,
since these observations were done in a specific period of the study and the observations could not
be repeated. A trained eye would maybe have obtained other results, which could have changed the
outcome of the faeces characteristics. This is not the case, however, since the observations have
been compared to the record of health among pigs and no incongruence was found.
54
General discussion of results and the study
6.3 Results from the study
The time of fishing the starfish was not optimal in relation to having the best possible product. It
was known that the CP content could be higher than at the time, given that the CP content in
starfish follow the reproduction cycle, i.e. the ovarian growth that is only at its beginning in the late
autumn (Oudejans and Vandersluis, 1979). However, due to a fixed time frame for the thesis, the
product used was having a lower CP content than known possible. This was not thought of as a
liability on the result of the study, since it was not an experiment done to see the results of the best
possible product, but rather the response on performance when feeding with the product well
knowing that it varies in quality. Using starfish fished when the amount of CP is high, however,
could have affected the interpretation of the results. A higher CP content would have made it
possible to include less SM and thereby the amount of Ca in the diet. On the contrary, the inclusion
level of SM in the diet would still have been put to a maximum, to see the piglet’s response on the
feed ingredient and the problem with high Ca level in the diet would possibly still be there.
No results in the present study can be considered immaterial since it is a new field of study, but
some results say more than others. It was rather difficult to interpret the difference observed on
some of the plasma parameters. Of the chosen blood parameters, only Ca and P contributed in
explaining the performance results. The concentration of Ca and P in plasma and the effect on
performance are well described in the literature (Maxson and Mahan, 1983; Koch et al., 1984;
Reinhart and Mahan, 1986; Gonzalez-Vega and Stein, 2014), thereby contributing to the
interpretation of the results. Contrary, the differences observed in both PUN and some of the AA
were rather difficult to interpret. The analysis on PUN and AA in plasma aimed to display no
difference in the protein sources, since the four diets were optimised to have the same content of
SID AA and only slightly differed in CP level. However, after viewing the results, this was not the
case. If blood samples had been taken before the beginning of the experiment, it could have given
appreciation in the individual pig’s PUN and plasma AA concentration. But doing that would be
considered as going too far, since it was not within the scope of the study. It can be speculated if
other blood parameters such as parathyroid hormone and calcitonin related to Ca homeostasis could
be of greater relevance and contribute to the explanation of the observed performance. However,
more blood parameters would most likely not have helped to interpret the results. It would,
however, have been appropriate to collect faeces samples as discussed above. On reflection,
collection of faeces and urine would maybe have helped in clarifying e.g. the bioavailability of P
and the possible formation of mineral complexes.
55
General discussion of results and the study
The study was financed by the project STARPRO, whose objective among other things was to
produce a 100% organic feed ingredient for pigs and poultry. The present study was conducted with
conventionally reared piglets and a conventionally designed diet containing conventional feed
ingredients and CAA. Interpretation of the results in relation to organic livestock production, must
therefore be considered in proportion to the differences in the production systems and the
constraints there are in rearing organic livestock, among these prohibition of supplementation to the
feed with CAA (Ministry of Food, 2015b). However, it is presumed, that as with any other feed
ingredient, SM can be included in diets for organic livestock, due to the content of CP and
composition of indispensable AA in SM.
6.4 Possibly same features in starfish meal and fish meal
What characteristics of SM that lead to the positive results of 5% SM in the diet for piglets is an
interesting question. It was reported by Whitson and Titus (1946) that SM contained the same
growth stimulating action as sardine FM when SM was used to supply the same amount of protein.
It was suggested that the growth stimulating action was due to the quantity of certain AA or
vitamins present in SM. It can be speculated if SM contains unknown positive factors on
performance as do FM. Traditionally, FM is recognised as a feed ingredient high in protein, energy,
vitamins and minerals with positive effect on performance (Cho and Kim, 2011). An increase in
ADG was presumably a result of increased ADFI as reported by Stoner et al. (1990). The increased
ADFI was suggested to be due to a preference by the pig for FM, where preference was thought to
be a function of taste or palatability. Though, other data illustrating what characteristic of taste or
palatability that makes pigs prefer FM have to my knowledge not been reported. Fish meal is a
major dietary source of n-3 PUFA (Cho and Kim, 2011). The perception of the n-3 PUFA in FM is
divided; some have reported that the n-3 PUFA has anti-inflammatory properties and benefits to the
immune system (Cho and Kim, 2011) while others have reported that n-3 PUFA made pigs more
susceptible to bacterial infections (Thies et al., 1999). In the present study, SM was analysed for FA
to compare the content of FA in SM with them of FM (Table 4). The idea was that if the two
products had similar FA composition, SM could have the same features as FM. Cho and Kim
(2011) reported that it is EPA and DHA of FM that benefits to the immune system. It has not been
possible to find a complete analysis of the composition of FA in FM, but it could be hypothesised
that SM and FM have similar contents of EPA and DHA. Therefore, SM may share the benefits or
poor effect of FA found on the immune system. In the light of these findings, it is definitely an area
worth to look into.
56
General discussion of results and the study
Table 4 - Fatty acid (FA) content (g FA/ 100 g FA) and iodine value (g/100 g fat) in starfish meal (SM) and in fish meal (FM).
g FA/100 g FA
Saturated
Formula
Name
Myristic acid
C15:0
Pentadecylic acid
C16:0
Palmitic acid
14.7
17.8
C18:0
Stearic acid
6.8
3.6
C20:0
Arachidic acid
0.4
C22:0
Behenic acid
0.2
C24:0
Lignoceric acid
0.0
Monounsaturated
Di- and tri unsaturated
11.4
6.0
1.5
34.9
C16:1 ω-9
Hexadecenoic acid
0.6
C16:1 ω-7
Palmitoleic acid
2.0
7.2
C18:1 ω-9
Oleic acid
2.0
12.3
Trans vaccenic acid
6.9
C18:1 ω-7
Vaccenic acid
0.7
C20:1 ω-9
Eicosenoic acid
21.7
C22:1 ω-11
Docosanoic acid
0.8
C22:1 ω-9
Erucic acid
1.5
C24:1 ω-9
Nervonic acid
2.0
Total monounsaturated fatty acids
6.6
7.7
38.1
C18:2 ω-6
Linoleic acid
0.4
C18:3 ω-6
γ-Linolenic acid
0.5
C18:3 ω-3
α-Linolenic acid
0.2
C20:2 ω-6
Eicosadienoic acid
0.7
C20:3 ω-6
Dihomo-γ-linolenic acid
0.1
C20:3 ω-3
Eicosatrienoic acid
0.2
Total di- and tri unsaturated fatty acids
unsaturated
FM2
C14:0
Total saturated fatty acids
≥ Tetra
SM1
2.1
1.93
2.0
C18:4 ω-3
Octadecatetraenoic acid
0.5
C20:4 ω-6
Arachidonic acid
4.0
2.4
C20:5 ω-3
Eicosapentaenoic acid
10.8
9.0
57
General discussion of results and the study
C22:5 ω-6
Osbond acid
1.1
C22:5 ω-3
Clupanodonic acid
1.2
2.6
C22:6 ω-3
Docosahexaenoic acid
7.0
6.6
Total ≥ tetra unsaturated fatty acids
24.5
Omega-6 fatty acids
6.7
Omega-3 fatty acids
19.8
Omega-6/omega-3
Iodine value (g/100g fat)
1
0.3
132.0
Caught November 5th 2014 in relation to the STARPRO project. The analysis was done by the Bligh and Dyer
extraction procedure (Jensen, 2008).
2
The values are from Sauvant et al. (2004).
3
Distribution between ω-6 and ω-3 is not known.
6.5 Possibility of further development of the product
Supplementation with chelators to the diet such as EDTA, citrate and phthalate have been found to
increase the efficiency of microbial phytase in hydrolysing phytic acid in vitro (Maenz et al., 1999).
It is thought that EDTA functions as a competitive chelator and minimise the formation of enzymeresistant mineral-phytate complexes. This observation is interesting, and could be of great interest
to follow up, since it maybe could contribute in solving the problem with the high Ca content in
SM. However, EDTA is not authorised in the EU to be used as additive in feed ingredients for
animals, and this can therefore only be considered as speculations and ideas for future studies. More
studies also need to be performed with the objective to find the maximum inclusion level of SM. In
this context, it could be appropriate to further develop the product and possibly in that way elevate
the inclusion level of SM. Levin et al. (1960) produced defatted SM made by the VioBin azeotropic
process (see paper) and found that protein concentrates prepared from defatted SM either by
pancreatic digestion or by washing with HCl, had high protein quality values, compared to good
quality FM. Further processing of SM could be of interest, but the cost of the processing must be
considered, so that the product can compete on price with e.g. FM.
58
Conclusion
CONCLUSION
From a theoretical aspect, the literature review stated that there is a need for alternative high-quality
protein sources, that is both sustainable and of local origin, and can fit the demands of organic feed
ingredients. Moreover, the increasing problems experienced with starfish in the Danish waters and
the chemical composition found in SM, together with the results found in studies with poultry,
make SM a realistic potential as feed ingredient for both conventional and organic reared piglets.
The level of energy, protein, vitamins and minerals are the main determinants of the level of
production that can be obtained, and are therefore of great importance. Protein sources of animal
origin provide the highest quality, primarily due to the composition of indispensable AA and,
therefore, the completeness of the protein source, making marine sources as SM more interesting as
feed ingredient.
Inclusion of 5% SM in the diet for piglets with BW 9-15 kg resulted in pig performance equal to
diets containing either FM or SPC. Starfish meal is therefore a potential competitor to high-quality
protein sources for piglets. Pigs fed 10% SM had lower ADG and G:F than pigs fed the other diets,
but results on ADFI was not significantly different among treatments. The negative effect on
performance when feeding the SM10% diet may be the high Ca level and wide Ca:P that affects
digestibility and absorption of P negatively. Moreover, binding of divalent minerals to phytic acid
and thus form mineral-phytate complexes, may reduce mineral bioavailability. The negative effects
increases as the dietary Ca:P increases. The determining factor for the maximum inclusion level of
SM in diets for piglets may be the dietary Ca level and the resulting Ca:P.
It is therefore concluded, that SM can be implemented in diets for piglets, and take part in the
compliance of the claim, that diets for organic reared livestock should constitute feed ingredients of
100% organic origin before the deadline in December 2017- assuming that it is legitimised due to
the promising results found until now. It is, however, still important to look into the effect on piglet
performance and possibly further develop the product, so higher inclusion level could be possible,
and moreover, for the product to win acceptance with farmers and secure a foothold as a highquality protein source.
59
Implications and perspectives
IMPLICATATIONS AND PERSPECTIVES
Inclusion of 5% SM in the diet for piglets with a BW of 9 to 15 kg, offers the same growth potential
as inclusion of traditional high-quality protein sources as FM and SPC. The performance response
to SM was similar in magnitude to that obtained with diets containing either FM or SPC, suggesting
that SM is a good alternative to known protein sources. Feeding a diet containing 10% SM to
piglets affected growth negatively, compared to feeding a diet containing either 5% SM, FM or
SPC. The current situation in which the need for alternative protein sources is requested should
encourage further investigation into the use of marine protein sources comprising SM as a mean of
achieving the goal of feed of 100% organic origin for organic livestock before the deadline in
December 2017.
A new study with SM for piglets in larger scale at a private conventional farm was planned to begin
in May 2015 as a dose response relationship. However, it was discontinued for want of
authorisation for the use of starfish as feed ingredient in the EU. In the first draft for the study, it
was planned to have three similar diets only differing in the content of FM and SM; one control diet
containing FM and two diets containing different levels of SM. These diets were to be feed for
piglets after weaning when the BW is expected to be 6 to 9 kg and in the following period (BW 9 to
16 kg). This study, when it becomes a reality, will hopefully answer questions in connection to SM,
about the products ability to sustain the positive effect on growth, also when fed to piglets that are
group stabled and therefore more challenged on health. Moreover, if the high G:F can be sustained.
60
Literature cited
LITERATURE CITED
Anonymous, 2000. Directive 200/60/EC of the European Parliament and of the Council of 23
October 2000 establishing a framework for Community action in the field of water policy.
Official Journal L327/1.
Asakawa, M., Nishimura, F., Miyazawa, K., Noguchi, T., 1997. Occurrence of paralytic shellfish
poison in the starfish Asterias amurensis in Kure Bay, Hiroshima Prefecture, Japan. Toxicon
35, 1081-1087.
Bejerholm, C., Mortensen, H.P., Madsen, A., 1990. Anvendelse af fiskemel i smågrise- og
ungsvineblandinger indflydelse på spise- og kødkvalitet, Slagteriernes Forskningsinstitut.
Retrieved on 5 May 2015 from
http://www.danishpigproduction.net/Publikationer/Kilder/sf_rap/sfr9005.aspx?full=1.
Bird, H.R., 1946. Dehydrated pea vines and starfish meal in poultry feeds, Studies on the marine
resources of sourthern New England. III the possibility of the utilization of starfish (Asterias
forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody Museum
of Natural History Yale University. Bingham Oceanographic Laboratory, New Haven, Conn.,
U.S.A.
Campbell, J.M., Crenshaw, J.D., Polo, J., 2013. The biological stress of early weaned piglets.
Journal of Animal Science and Biotechnology 4.
Cervantes-Pahm, S.K., Stein, H.H., 2010. Ileal digestibility of amino acids in conventional,
fermented, and enzyme-treated soybean meal and in soy protein isolate, fish meal, and casein
fed to weanling pigs. Journal of Animal Science 88, 2674-2683.
Chittavong, M., Jansson, A., Lindberg, J.E., 2013. Effects of high dietary sodium chloride content
on performance and sodium and potassium balance in growing pigs. Tropical Animal Health
and Production 45, 1477-1483.
Cho, J.H., Kim, I.H., 2011. Fish meal - nutritive value. Journal of Animal Physiology and Animal
Nutrition 95, 685-692.
Dare, P.J., 1982. NOTES ON THE SWARMING BEHAVIOR AND POPULATION-DENSITY
OF ASTERIAS-RUBENS L (ECHINODERMATA, ASTEROIDEA) FEEDING ON THE
MUSSEL, MYTILUS-EDULIS-L. Journal Du Conseil 40, 112-118.
Demeyer, M., De Winter, J., Caulier, G., Eeckhaut, I., Flammang, P., Gerbaux, P., 2014. Molecular
diversity and body distribution of saponins in the sea star Asterias rubens by mass
61
Literature cited
spectrometry. Comparative Biochemistry and Physiology B-Biochemistry & Molecular
Biology 168, 1-11.
Dong, G., Xu, T.H., Yang, B., Lin, X.P., Zhou, X.F., Yang, X.W., Liu, Y.H., 2011. Chemical
Constituents and Bioactivities of Starfish. Chem. Biodivers. 8, 740-791.
Edebo, L., Haamer, J., Lindahl, O., Loo, L.O., Piriz, L., 2000. Recycling of macronutrients from sea
to land using mussel cultivation. International Journal of Environment and Pollution 13, 190207.
EGTOP, 2015. Final Report. Feed Mandate II, Expert Group for Technical Advice on Organic
Production (EGTOP). European Commission - Agriculture and Rural Development.
Directorate B. Multilateral rrelations, quality policy. Retrieved on 4 August 2015 from
http://ec.europa.eu/agriculture/organic/eu-policy/expert-advice/documents/final-reports/egtopfinal-report-feed-ii_en.pdf.
Fearnside, P.M., 2001. Soybean cultivation as a threat to the environment in Brazil. Environmental
Conservation 28, 23-38.
Gonzalez-Vega, J.C., Stein, H.H., 2014. Calcium Digestibility and Metabolism in Pigs. AsianAustralasian Journal of Animal Sciences 27, 1-9.
Gonzalez-Vega, J.C., Walk, C.L., Liu, Y., Stein, H.H., 2013. Endogenous intestinal losses of
calcium and true total tract digestibility of calcium in canola meal fed to growing pigs. Journal
of Animal Science 91, 4807-4816.
Grela, E.R., Matras, J., Pisarski, R.K., Sobolewska, S., 2012. The effect of supplementing organic
diets with fish meal and premix on the performance of pigs and some meat and blood
characteristics. Polish Journal of Veterinary Sciences 15, 379-386.
Gudbjarnason, S., 1999. Bioactive marine natural products. Rit Fiskideildar 16, 107-110.
Hallenstvedt, E., Kjos, N.P., Rehnberg, A.C., Overland, M., Thomassen, M., 2010. Fish oil in feeds
for entire male and female pigs: Changes in muscle fatty acid composition and stability of
sensory quality. Meat Science 85, 182-190.
Heo, J.M., Opapeju, F.O., Pluske, J.R., Kim, J.C., Hampson, D.J., Nyachoti, C.M., 2013.
Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control
post-weaning diarrhoea without using in-feed antimicrobial compounds. Journal of Animal
Physiology and Animal Nutrition 97, 207-237.
62
Literature cited
Hertzman, C., Goransson, L., Ruderus, H., 1988. INFLUENCE OF FISH-MEAL, RAPESEED,
AND RAPESEED MEAL IN FEED ON THE FATTY-ACID COMPOSITION AND
STORAGE STABILITY OF PORCINE BODY-FAT. Meat Science 23, 37-53.
Heuser, G.F., McGinnis, J., 1946. Starfish meal in chick rations, Studies on the marine resources of
sourthern New England. III the possibility of the utilization of starfish (Asterias forbesi desor),
Bulletin of the Bingham Bingham Oceanographic collection. Peabody Museum of Natural
History Yale University. Bingham Oceanographic Laboratory, New Haven, Conn., U.S.A.
Hoffman, J.R., Falvo, M.J., 2004. Protein - Which is best? Journal of Sports Science and Medicine
3, 118-130.
Holtegaard, L.E., Gramkow, M., Petersen, J.K., Dolmer, P., 2008. Biofouling og Skadevoldere:
Søstjerner, Dansk Skaldyrscenter. Available at: http://www.skaldyrscenter.dk.
Hutchinson, G.E., Setlow, J.K., Brooks, J.L., 1946. Biochemical observations on Asterias forbesi,
Studies on the marine resources of sourthern New England. III the possibility of the utilization
of starfish (Asterias forbesi desor), Bulletin of the Bingham Bingham Oceanographic
collection. Peabody Museum of Natural History Yale University. Bingham Oceanographic
Laboratory, New Haven, Conn., U.S.A.
Jensen, S.K., 2008. Improved Bligh and Dyer extraction procedure. Lipid Technology 20, 280-281.
Jezierny, D., Mosenthin, R., Bauer, E., 2010. The use of grain legumes as a protein source in pig
nutrition: A review. Animal Feed Science and Technology 157, 111-128.
Jonsdottir, R., Valdimarsdottir, T., Baldursdottir, B., Thorkelsson, G., 2003. Influence of low fat
fishmeal on fatty acid composition and sensory quality of pork. Journal of Muscle Foods 14,
51-65.
Jørgensen, L., 2004. Smågrisefoder uden fiskemel. Meddelelses nr. 652, Pig Research Centre,
Copenhagen, Denmark. Retrieved on 23 July 2015 from
http://vsp.lf.dk/Publikationer/Kilder/lu_medd/2004/652.aspx.
Jørgensen, L., 2012. Råvarer - Maks. indhold, Pig Research Centre, Copenhagen, Denmark.
Retrieved on 13 July 2015 from
http://vsp.lf.dk/Viden/Foder/Opslagstavlen/Raavarer_max%20indhold.aspx.
Kim, S.W., Easter, R.A., 2001. Nutritional value of fish meals in the diet for young pigs. Journal of
Animal Science 79, 1829-1839.
Kjølhede, V., 2015. Chairman at Foreningen Muslingeerhvervet. Personal communication, June 14
2015, Hanstholm, Denmark.
63
Literature cited
Koch, M.E., Mahan, D.C., Corley, J.R., 1984. AN EVALUATION OF VARIOUS BIOLOGICAL
CHARACTERISTICS IN ASSESSING LOW PHOSPHORUS INTAKE IN WEANLING
SWINE. Journal of Animal Science 59, 1546-1556.
Lalles, J.P., Bosi, P., Smidt, H., Stokes, C.R., 2007. Nutritional management of gut health in pigs
around weaning. Proceedings of the Nutrition Society 66, 260-268.
Lenis, N.P., Jongbloed, A.W., 1999. New technologies in low pollution swine diets: Diet
manipulation and use of synthetic amino acids, phytase and phase feeding for reduction of
nitrogen and phosphorus excretion and ammonia emission - Review. Asian-Australasian
Journal of Animal Sciences 12, 305-327.
Levin, E., Rand, N.T., Mosser, J.D., Varner, D.S., Collins, V.K., 1960. DEFATTED STARFISH
MEAL AS SOURCE OF NUTRIENTS IN POULTRY RATIONS. Poultry Science 39, 646654.
Maenz, D.D., Engele-Schaan, C.M., Newkirk, R.W., Classen, H.L., 1999. The effect of minerals
and mineral chelators on the formation of phytase-resistant and phytase-susceptible forms of
phytic acid in solution and in a slurry of canola meal. Animal Feed Science and Technology 81,
177-192.
Maribo, H., 2010. Fodring af smågrise Pig Research Centre, Copenhagen, Denmark. Retrieved on
12 February 2015 from
http://vsp.lf.dk/Viden/Foder/Tildeling%20af%20foder/Fodring%20af/Fodring%20af%20smaag
rise.aspx?full=1.
Mason, G.D., Scott, D., 1974. RENAL EXCRETION OF SODIUM AND SODIUM TOLERANCE
IN PIG. Quarterly Journal of Experimental Physiology and Cognate Medical Sciences 59, 103112.
Maxson, P.F., Mahan, D.C., 1983. DIETARY CALCIUM AND PHOSPHORUS LEVELS FOR
GROWING SWINE FROM 18 TO 57 KILOGRAMS BODY-WEIGHT. Journal of Animal
Science 56, 1124-1134.
Metzler, B.U., Mosenthin, R., Baumgartel, T., Rodehutscord, M., 2008. The effect of dietary
phosphorus and calcium level, phytase supplementation, and ileal infusion of pectin on the
chemical composition and carbohydrase activity of fecal bacteria and the level of microbial
metabolites in the gastrointestinal tract of pigs. Journal of Animal Science 86, 1544-1555.
Ministry of Food, A.a.F., 2015a. Surveillance by the Danish monitoring program on toxic and
potentially toxic algae/phytoplankton in rerlation to mussel fishery., Retrieved on 15 June 2015
64
Literature cited
from http://www.foedevarestyrelsen.dk/Kontrol/Muslingeovervaagning/Muslingeovervaagning
_Danmark/Sider/Danmark_muslingovervaagning.aspx?Indgang=Kontrol&Indgangsemne=Mus
lingeoverv%c3%a5gning&.
Ministry of Food, A.a.F., 2015b. Vejledning om økologisk jordbrugsproduktion, Ministeriet for
Fødevarer, Landbrug og Fiskeri, Center for Kontrol, jordbrugskontrol,
NaturErhvervsstyrrelsen, Copenhagen, Denmark. Retrieved on 21 April 2015 from
http://naturerhverv.dk/tvaergaaende/oekologi/jordbrugsbedrifter/vejledning-om-oekologiskjordbrugsproduktion/#c5462.
Morse, R.E., Griffiths, F.P., Parkhurst, R.T., 1946. Preliminary report on eight weeks of
comparative feeding of protein equivalent diets containing fish meal, crab meal, and starfish to
Rhode Island red chicks, Studies on the marine resources of sourthern New England. III the
possibility of the utilization of starfish (Asterias forbesi desor), Bulletin of the Bingham
Bingham Oceanographic collection. Peabody Museum of Natural History Yale University.
Bingham Oceanographic Laboratory, New Haven, Conn., U.S.A.
Nicholas, P., Padel, S., Sundrum, A., 2007. Guidance notes to operators including recommendations
in relation to nutrient supply. EEC 2092/91 (Organic Revision Project Report), no. D 4.3.,
University of Wales, Aberystwyth, Insitute of Rural Sciences. Retrieved on 26 May 2015 from
http://www.orgprints.org/13342/1/D_4_3_Feed_Guidance_Notes_October_2007.pdf.
Nielsen, P., Canal-Vergés, P., Gietner, K., Nielsen, C.F., Petersen, J.K., 2014. Konsekvens
vurdering af fiskeri på blåmuslinger og søstjerner i Løgstør Bredning 2014/2015. DTU Aquarapport nr. 285-2014.
Nofrarias, M., Manzanilla, E.G., Pujols, J., Gibert, X., Majo, N., Segales, J., Gasa, J., 2006. Effects
of spray-dried porcine plasma and plant extracts on intestinal morphology and on leukocyte cell
subsets of weaned pigs. Journal of Animal Science 84, 2735-2742.
Norgaard, J.V., Hansen, M.J., Soumeh, E.A., Adamsen, A.P.S., Poulsen, H.D., 2014. Effect of
protein level on performance, nitrogen utilisation and carcass composition in finisher pigs. Acta
Agriculturae Scandinavica Section a-Animal Science 64, 123-129.
NRC, 2012. Nutrient requirement of swine, 10th Ed. National Academy Press, Washington, DC.
Nørgaard, J.V., Pedersen, C., Tybirk, P., Sloth, N.M., 2012. Chapter 22. Requirement for and
evaluation of dietary protein and amino acids, Nutritional physiology of pigs - With emphasis
on Danish production conditions, Pig Research Centre, Copenhagen, Denmark. Retrieved on 1
July 2015 from http://vsp.lf.dk/Viden/Laerebog_fysiologi/Contents.aspx.
65
Literature cited
Nørgaard, J.V., Petersen, J.K., Tørring, D.B., Jørgensen, H., Lærke, H.N., 2015. Chemical
composition and standardized ileal digestibility of protein and amino acids from blue mussel,
starfish, and fish silage in pigs. Animal Feed Science and Technology 205, 90-97.
Oudejans, R., Vandersluis, I., 1979. CHANGES IN THE BIOCHEMICAL COMPOSITION OF
THE OVARIES OF THE SEASTAR ASTERIAS-RUBENS DURING ITS ANNUAL
REPRODUCTIVE-CYCLE. Mar. Biol. 50, 255-261.
Peo, E.R., Jr., 1991. Calcium, phosphorus, and vitamin Din swine nutrition, In: Miller, E.R., Ullrey,
D.E., Lewis, A.J. (Eds.), Swine Nutrition, Stoneham, MA: Butterworth-Heinemann, pp. 165182.
Petersen, J.K., 2015. Professor at DTU AQUA. Institut for Akvatiske Ressourcer. Dansk
Skaldyrcenter. Personal communication, June 3 2015.
Petersen, J.K., Hasler, B., Timmermann, K., Nielsen, P., Torring, D.B., Larsen, M.M., Holmer, M.,
2014. Mussels as a tool for mitigation of nutrients in the marine environment. Marine Pollution
Bulletin 82, 137-143.
Petersen, J.K., Timmermann, K., Carlsson, M., Holmer, M., Maar, M., Lindahl, O., 2012. Mussel
farming can be used as a mitigation tool - A reply. Marine Pollution Bulletin 64, 452-454.
Pluske, J.R., Hampson, D.J., Williams, I.H., 1997. Factors influencing the structure and function of
the small intestine in the weaned pig: a review. Livestock Production Science 51, 215-236.
Rasmussen, D., K., Vinther, J., 2015. Energiindhold i foder til smågrise. Meddelelse nr. 1034, Pig
Research Centre, Copenhagen, Denmark. Retrieved on 27 June 2015 from
http://vsp.lf.dk/Publikationer/Kilder/lu_medd/2015/1034.aspx.
Reinhart, G.A., Mahan, D.C., 1986. EFFECT OF VARIOUS CALCIUM - PHOSPHORUS
RATIOS AT LOW AND HIGH DIETARY PHOSPHORUS FOR STARTER, GROWER
AND FINISHING SWINE. Journal of Animal Science 63, 457-466.
Ringrose, R.C., 1946. Starfish meal feeding experiment with chicks, Studies on the marine
resources of sourthern New England. III the possibility of the utilization of starfish (Asterias
forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody Museum
of Natural History Yale University. Bingham Oceanographic Laboratory, New Haven, Conn.,
U.S.A.
Sauvant, D., Perez, J.-M., Tran, G., 2004. Tables of composition and nutritional value of feed
materials: Pigs, poultry, cattle, sheep, goats, rabbits, horses and fish The Institut National de la
66
Literature cited
Recherche Agronomique (INRA), the Association Française de Zootechnie (AFZ) and the
Institut National Agronomique Paris-Grignon.
Sieradzki, Z., Walczak, M., Kwiatek, K., 2006. Occurrence of genetically modified maize and
soybean in animal feedingstuffs. Bulletin of the Veterinary Institute in Pulawy 50, 567-570.
Smith, J., Gerrard, C., Hermansen, J., 2014. Improved contribution of local feed to support 100%
organic feed supply to pigs and poultry. Synthesis report, CORE organic II, Denmark.
Stoner, G.R., Allee, G.L., Nelssen, J.L., Johnston, M.E., Goodband, R.D., 1990. EFFECT OF
SELECT MENHADEN FISH-MEAL IN STARTER DIETS FOR PIGS. Journal of Animal
Science 68, 2729-2735.
Stuart, H.O., Hart, C.P., 1946. Starfish meal as a protein substitute in chick rations, Studies on the
marine resources of sourthern New England. III the possibility of the utilization of starfish
(Asterias forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody
Museum of Natural History Yale University. Bingham Oceanographic Laboratory, New Haven,
Conn., U.S.A.
Stutz, M.W., Matterson, L.D.S., 1964. METABOLIZABLE ENERGY VALUES +
COEFFICIENTS OF DIGESTIBILITY FOR PROTEIN + FAT OF STARFISH MEAL +
STARFISH MEAL COMBINED WITH FISH MEAL. Poultry Science 43, 474-&.
Sundrum, A., Schneider, K., Richter, U., 2005. Possibilities and limitations of protein supply in
organic poultry and pig production. Final Project Report EEC 2092/91 (Organic) Revision, no.
D 4.1 (Part 1). University of Kassel, Witzenhausen, Department of Animal Nutrition and
Animal Health. Retrieved on 26 May 2015 from http://www.organicrevision.org/pub/Preliminary_Report_Feed_EC2092_Revision_WP4_1.pdf.
Tausen, A.H., 2012. Chapter 19. Feed intake and energy supply - growing pigs, Nutritional
physiology of pigs - With emphasis on Danish production conditions, Pig Research Centre,
Copenhagen, Denmark. Retrieved on 1 July 2015 from
http://vsp.lf.dk/Viden/Laerebog_fysiologi/Contents.aspx.
Thies, F., Peterson, L.D., Powell, J.R., Nebe-von-Caron, G., Hurst, T.L., Matthews, K.R.,
Newsholme, E.A., Calder, P.C., 1999. Manipulation of the type of fat consumed by growing
pigs affects plasma and mononuclear cell fatty acid compositions and lymphocyte and
phagocyte functions. Journal of Animal Science 77, 137-147.
Todd, J.R., Lawson, G.H.K., Dow, C., 1964. EXPERIMENTAL STUDY OF SALT POISONING
IN PIG. Journal of Comparative Pathology and Therapeutics 74, 331-&.
67
Literature cited
Torrallardona, D., Conde, M.R., Badiola, I., Polo, J., Brufau, J., 2003. Effect of fishmeal
replacement with spray-dried animal plasma and colistin on intestinal structure, intestinal
microbiology, and performance of weanling pigs challenged with Escherichia coli K99. Journal
of Animal Science 81, 1220-1226.
Tybirk, P., Sloth, N.M., Jørgensen, L., 2014. Nutrient Requirement Standards. 19th edition of the
Danish nutrient standards. Revised 24 April 2014. , Pig Research Centre, Copenhagen,
Denmark. Retrieved on 12 February 2015 from
http://www.pigresearchcentre.dk/About%20us/Nutrient%20standards.aspx.
Varley, P.F., Callan, J.J., O'Doherty, J.V., 2011. Effect of dietary phosphorus and calcium level and
phytase addition on performance, bone parameters, apparent nutrient digestibility, mineral and
nitrogen utilization of weaner pigs and the subsequent effect on finisher pig bone parameters.
Animal Feed Science and Technology 165, 201-209.
VSP, 2014. EFSA rapport om PED-virus og VSP's anefalinger vedrørende brug af blodplasma, Pig
Research Centre, Copenhagen, Denmark. Retrieved on 13 July 2015 from
http://vsp.lf.dk/Aktuelt/Nyheder/2014/11/171114_PED.aspx.
VSP, 2015. Fodermiddeltabel og beregning af I-faktor samt fordøjeligt indhold, Pig Research
Centre, Copenhagen, Denmark. Retrieved on 22 July 2015 from
http://vsp.lf.dk/Services/Beregninger/Fodermiddeldatabase.aspx.
Whitson, D., Titus, H.W., 1946. The use of starfish meal in chick diets, Studies on the marine
resources of sourthern New England. III the possibility of the utilization of starfish (Asterias
forbesi desor), Bulletin of the Bingham Bingham Oceanographic collection. Peabody Museum
of Natural History Yale University. Bingham Oceanographic Laboratory, New Haven, Conn.,
U.S.A.
Zervas, S., Zijlstra, R.T., 2002. Effects of dietary protein and oathull fiber on nitrogen excretion
patterns and postprandial plasma urea profiles in grower pigs. Journal of Animal Science 80,
3238-3246.
Zhang, G.-y., Ren, H.-H., Zhang, Y.-B., Ma, L.-Q., Yang, Y.-L., Wang, S., 2013. Chemical
constituents of the starfish Asterias rollestoni Bell. Biochemical Systematics and Ecology 51,
203-206.
68