50
Short Communications / Kort Mededelings
Chemical compositionof carcasssawdust
residue as a predictor of the chemical
compositionof sheepcarcasses
S.W.Kock,J.B.J.van Ryssenand
DebbieG. Davies*
Departmentof AnimalScienceand PoultryScience,University
of Natal,PrivateBag X01, Scottsville,
Pietermaritzburg,
3209
Republicof SouthAfrica
Reteived
SAugu.st
1994;revisedl3 Murch 1995;uccepted
I3 Murch 1995
Twenty sheep,ranging in body massfrom 25 to 62 kg, were slaughtered to comparetwo methodsof estimatingthe chemicalcomposition of the carcass.One half of eachcarcasswas ground in a carcass
grinder equipped with a 6 mm sieve and a representativesample
taken. The other half was frozen. The complete frozen half was
'chop' portionswith
sawedat 25 mm intervalsinto
a bandsaw.The
tissueresiduein the saw was collected.Moisture,fat, proteinand ash
percentages
of the sampleswere determined.The meancomposition
of the ground carcassand sawdustsampleswere respectively:moisture: 56.4 and 55.j%o(/ = 0.137); fat 21.2 and 23.l7o (/ = 0.923);
protein: 16.6 and l6.1Vo(/ = 0.154) and ash:4.7 and 5.5Vo(y' =
0.235).The correlationsbetweensamplingtechniquescomparewell
with similarcomparisonsobtainedfrom studieswith cattleandpigs.
This suggeststhat a reliableestimateof the fat and moisturecontent
of the carcasscan be obtainedfrom the sawdustresidue.The technique can be recommendedfor use in growth and feedingtrials with
sheepat locationswhere sophisticatedinstrumentsare not available
to measurecarcasscomposition.
'n
van tussen25 en 62 kg is
Twintig skape met
liggaamsmassa
geslagom twee metodesom die chemiesesamestellingvan karkasse
'n
'n
karkasmeule
te bepaal,te vergelyk. Halwe karkasvan elk is in
'n
'n
met 6 mm sif gemaalen monsteris geneem.Die anderhelfteis
gevries.Die heelgevriesdehelfteis in 25 mm 'kotelet'-stukke
met'n
'n
monsteris van die weefselresiduin die saag
bandsaaggesaagen
geneem.Vog-, vet-, proteien- en asbepalingsvan die monstersis
gedoen.Die gemiddeldesamestellingvan die gemaalde-en saagmonsterswas respektieweliksoos volg: vog: 56.4 en 55.0Vo(f =
0.137);vet: 2l .2 en 23.17o(y' = 0.923):proteien:16.6en 16.lVo(y'
= 0.154) en as: 4.7 en 5.57oG = 0.235). Die korrelasiestussen
metodes van monsternemingstem goed ooreen met soortgelyke
vergelykingsvan bees-en varkkarkasse.
Die resultatedui daaropdat
van monsternemingbetroubareskattingsvan
die saagresidu-metode
gee. Die metodekan by
die vet- en voginhoud van skaapkarkasse
groei- en voedingsproewemet skapeaanbeveelword in omstandighedewaar gesofistikeerde
instrumenteom die bepalingste doen,nie
beskikbaaris nie.
Keywords: Carcass chemical composition, fat, protein, ash,
sawdust residue, sheep.
* To whom correspondence
shouldbe addressed
In any growth and feeding study on animals, knowledge of the
chemical composition of the carcassor the empty body is valuable for proper evaluation of responsesto treatments.A standard
(2)
S.Afr.Tydskr.
Veek..
199
5.25
methodfor determiningthe compositionof a carcassis to grind
up the carcassandto analysea samplefor moisture,protein,fat
andash(Shieldset a\.,1983).This procedure
is expensive
dueto
the needfor expensive
grindingequipmentandbecausethe meat
is greatly devalued.Variousindirect approachesand methods
havebeenproposedto estimatebody and carcasscomposition.
Thesemethodsincludemeasuringthe compositionof the 9-10I I th rib cut; dissectionof the carcassinto fat, bone and lean
meat;determiningthe thicknessof the fat over the eye muscle
(m.longissimus
dorsi)at specificpointson the back;determining
the specificgravityof the carcass;usingureaand other dilution
techniques;implementingmagneticresonanceimaging; etc.
(Reid et al., 1955;Hansard,1961;Berg & Butterfield,1976,
K ock& P reston,
1979;Ful l eret a1.,1990).
Vanceet ol. (1970)demonstrated
that the chemicalcomposition of untrimmed,wholesalebeef cuts correspondedwell
with the compositionof the residuein the saw,collectedwhen
the frozencarcasses
were slicedinto 25 rnm cuts.Williams et
al. (1974)conducteda similarstudyand reportedcorrelations
betweenthe tissuesawdustresiduefrom frozenbeefcarcasses
and the ground carcassesof 0.82, 0.94, 0.64 and 0.68 for
moisture,fat, proteinand ashpercentages
respectively.A similar observation
was madeby Shieldset al. (1983)on pig carcasses.This sawdust technique does not seem to have
receivedmuch applicationin studieson cattle or pigs. The
reasonscould be that, in cattle,the sawingof carcasses
into
25 mm cuts is not done commercially,and in pigs the more
simple method of measuringbackfat thickness is widely
acceptedin the determination
of carcasscomposition.On the
other hand,the sawingof a whole sheepcarcassinto 'chop'
portionsis frequentlydonecommerciallyand doesnot render
the meat unfit or unacceptable
for human consumption.The
useof the meatresidueaccumulated
during sawingto predict
the chemicalcompositionof the carcassseemsa feasibleand
inexpensive
methodof obtainingan objectivemeasurement
of
the carcasscompositionof sheepusedin growth and feeding
trials.This investigationwas conductedto establishwhether
the compositionof carcasssawdustis reliable in estimating
actualcarcasscompositionof sheep.
Twenty SA Mutton Merino sheep,rangingfrom 25 to 65 kg
live massand 9 to 24 monthsof age,were slaughtered.
The
head,skin, internalorgansand digestivetract were removed
to obtainthe carcass(includingthe kidney fat), as available
commercially.Each carcasswas carefully split in half along
the spine. Once chilled, one half, taken at random, was
ground three times through a carcass/meat
grinder (Autio
Company,Astoria,Oregon,USA) with a final sieve size of
6 mm, and a representative
sampletaken.The other half of
the carcasswas frozen (- 20 'C) before being cut into 'chop'
portions at regular intervalsof 25 mm with a bandsaw.The
frozen ribs, sternumand flank were sawed into strips of 25
mm. The residuethat accumulatedduring the sawing of each
carcasswas collected,mixed thoroughly and sampled.The
temperaturein the laboratorywas kept at below 10"C during
these samplepreparationsto minimize moisture loss. The
sampleswere frozen pending moisture,fat, protein and ash
analyses.
Moisture content was determinedin a forced circulation
oven at 100'C. The fat (lipid) was extractedfrom a separate
samplein a two-stepprocess,involving the removal of surplus fat using petroleumether,followed by the extractionof
S . A t i . J . A n i m . S c iI.9. 9 5 . 2 5 ( 2 )
ll
Table 1 Mean carcasscomposition(t std) of the
groundcarcassas comparedto that obtainedfrom
the residuein the meatsaw
Composition*
Ground
Sawdust
CYTo
CYTo
,i(adj)
Moisture
5 6 . 4r 4 . 8 2 4 . 1 5 5 . 0t - 5 . 1 2 5 . 7
0.13',7
Fat
2 1 . 2 * 5 . 1 2 , 5 . 3 2 3 . 1t 5 . 8 2 9 . 3
0.923
Protein
1 6 . 6t 2 . 0
9.8
1 6 . lt I . 5
1. 6
0.r54
Ash
4 . 1t 1 . 2
,s.9
5 . 6t | . 0
4.9
0.235
* D i f f e r e n c e sb e t w e e ns a r n p l i n gt e c h n i q u e as r en o t s i g n i f i c a n t
the remainingfat with petroleumetherin a Soxlettfat extraction apparatus(Kock & Preston,l9l9). Protein (N x 6.25)
were determinedon the fat-freesamand ash concentrations
ple - protein using the Kjeldahl technique(AOAC, 1985)
and ash in a muffle furnaceat 450'C. The data were comparedstatistically,using a Minitab statisticalpackage(Mini ta b , r eleas e9 t or Wi n d o w s , 1 9 9 3 , M i n i ta b In c. 3081
EnterpriseDrive, StateCollege,PA, USA).
The mass of the frozen carcassesranged from 11.0 to
3 0 . 2 k g w i t h a m e a no f 2 2 . 0 + 5 . 1 9 k g . T h e c o m p o s i t i oonf
sampledaccordingto the two methods,is prethe carcasses.
of the predictedfat percentsentedin Table l. The regression
age (ground)on observedfat percentage(sawdust)is depicted
in Figure 1. The regressionequationsfor sawdustsample
(SAW) on groundsample(GR) were as follows:
Fat GR = 1.96+ 0.832fat SAW
WarerGR = I 1.6+ 0.814waterSAW
Pr ot einG R = 7. 36 + 0 .5 7 5P ro te i nS AW
As h G R = 1. 30+ 0 .6 3 0A s h SA W
(r2= 0.923)
(r2- 0.737)
(r?= 0 .154)
(r2= 0 .235)
The high correlationbetweenthe two samplingtechniquesfor
supportthe results,
the f at andmoisturecontentof the carcasses
resiof sawdust
obtainedon cattleandpigs,thatthecomposition
duecanbe usedto predictthefat andwatercontentof wholecar( W illiam set a\.,1 9 1 4 Sh
to
; i e l d se r a l ., 1 9 8 3 ).Ac c ordi ng
ca ss es
Fo rtinet ol. ( 1981)b, o d yta t i s th e m o s ti m p o rta npt a r ameterof
study,fat content
thenutritionalstatusof the body.In thepresent
riingedfrom 9.4 to 29.2Vc,thuscoveringa wide rangeof carcass
conditions.The predictionof carcassfat and moisturecontent
basedon sawdust
residuesamples
shouldgivea reliableestimate
of true carcasscomposition.The correlationscoefficients(r)
betweenfat andmoistureconcentrations
of the groundcarcasses
andthe sawdustresidues
were-0.814 and- 0.925respectively.
These high negativecorrelationsagreed well with results
(Reidet al., 1955;Williamset el..
obtainedin cattlecarcasses
1974) and support the well-documentedinverse relationship
which is usedin many formulaeto calculatebody composition
(Maynardet al., 1919).
Ash and proteinconcentrations
showedvery low correlations between sampling techniques.The small variation
within proteinand ashconcentrations
might havecontributed
to theserelativelylow correlationsfor thesecomponents.A
similarlylow correlationwasreportedby Shieldset al. ( 1983)
betweenash concentrationsobtainedfrom the whole carcass
sampleand a sawdustresiduesampleof pig carcasses.
The
sawdustsamplecontaineda higher,though not statistically
significant,ash contentthan the ground sample.This may
indicatethat bone createdslightly more sawdustthan soft tissue,thus signifyinga point of inaccuracyin the tissuesawdust method.Reid er al. (1955) reportedthat the proteinand
ash contentof the empty,fat-freebovine body is practically
constantat 807oand 20Vorespectively,irrespectiveof type of
animalor sex.This was confirmedin other mammals(Maynard et al., 7979).When the protein and ash contentswere
calculatedon a dry, fat-freebasis(Thble2), the composition
of the carcassremainedrelativelyconstant,althoughpercentages were slightly different to those reported for the empty
body (Reid et al., 1955;Hansard,1967).This suggeststhat a
determinationof only the fat percentagein a carcassshould
providevaluableinformationregardingthe chemicalcompositionof the carcass.
Table 2 Percentageproteinand ash
(t std) in the dry, fat-freecarcasses,
obtainedfrom a groundcarcassand a
sawdustresiduesample
Ground
Sawdust
P r o t e i n x( % )
1 1. 9 t 3 . 9 9
7 4 . 7t 3 . 8 5
Ash* (7o)
2 2 . 1t 3 . 9 8
2 5 . 3t 3 . 8 5
* Differencesbetweensampling techniquesare
notsignificant
&
32
a
s24
()
(d
;16
tL8
0816243240
Fat"/" (sawdust)
Figure I Regressionof the fat percentagein sawdustsampleson
thatin the groundcarcasssamples,Y = 196+ 0.832X, y' = 0.923
The resultsof the presentinvestigation
suggestthat an analysis of the compositionof the sawdustresiduecan be recommendedfor estimatingthe fat and moisturecontent in the
carcassof sheepat the end of a feedingtrial. The methoddoes
not havethe accuracyof sophisticated
instrumentsand techniqueswhich canbe conductedat well-equippedlaboratories.
However, this techniquewould probably provide a more
accurateand objectiveestimateof carcassfat contentthan a
carcassgradeand can replaceor complementcarcassgrading
in field experiments.
The investigationdid not include carcassesfrom fat-tailedand f-at-rumped
sheepand further investigations would be required before the sawdust residue
techniquecan be recommendedwhere these types of carcassesare involved.Furthermore,the analytical technique
52
usedto measurethe fat contentin the samplescan be simplifled and improved by freeze-drying the samples before
extractingthe tat.
Fortin et al. (1981) pointedout that the predictionof carcasscompositionusing the specificgravity techniqueis too
variable to allow for comparisonson an individual animal
basis,althoughthe techniqueis quite suitablefor groupcomparisons.Likewise, a comparisonof the chemicalcomposition of sawdustamong treatmentgroups would probably be
on an individual
morereliablethanthe evaluationof carcasses
at
basis,consideringthat variationin fat contentof carcasses
the end of a feedingtrial would probablybe lessthan the variationusedin the presentinvestigation.
References
AOAC, 1985.Official methodsof analysis(l3th edn).Associationof Official
Analytical Chemists,Inc. Arlington, Virginia, USA.
BERG, R.T. & BUTTERFIELD, R.M., 1976.New conceptsof cattlegrowth.
SydneyUniversityPress,Sydney,Australia.
FORTIN, A., REID, J.T.,SIMPFENDORFER,S., AYALA, H.J.,ANRTQUE,
R . , K E R T Z , A . F . ,M A I G A , A . M . , S I M , D . W . & W E L L I N G T O N , G . H . ,
1 9 8 1 .C h e m i c a l c o m p o s i t i oann d c a r c a s s p e c i f i cg r a v i t yi n c a t t l e : e f f e c t
of level of energyintake and influenceof breedand sex.Cun.J. Anim. Sci.
62,8',71-882.
F U L L E R , M . F . , F O W L E R , P . A . ,M c N E I L L , & F O S T E R ,M . A . , 1 9 9 0 .B o d y
composition:the precisionand accuracyof new methodsand their
suitabilityfor longitudinalstudies.Proc. Nutr. Srx:.49,423426.
H A N S A R D , S . L . , 1 9 6 7 .E v a l u a t eg r o w t hi n t e r m so f b o d yc o m p o s i t i o n
of the
a n i m a l .F e e dB a g R e d B o o k . p p . 1 4 7 - 1 5 6 .M i l l e r P u b l .C o . , M n , U S A
KOCK, S.W. & PRESTON, R.L., 1979.Estimationof bovine carcass
compositionby the urea dilution technique.J. Anim. Sci. 48, 319-32'7.
M A Y N A R D , L . A . , L O O S L I , J . K . ,H I N T Z , H . F . & W A R N E R ,R . G . , I 9 7 9 .
Animal Nutrition. 7th edn. McGraw-Hill, New York.
R E I D , J . T . ,W E L L I N G T O N , G . H . & D U N N , H . O . , 1 9 5 5 .S o m er e l a t i o n s h i p s
amongthe major chemicalcomponentsof the bovine body and their
J. Duiry Sci. 38, 1344-1359.
applicationto nutritionalinvestigations.
S H I E L D S ,R . G . ,M A H A N , D . C . & C A H I L L , V . R . , 1 9 8 3 .A c o m p a r i s o n
of
methodsfbr estimatingcarciLss
and empty body compositionin swine
fionr birth to 145kg. J. Anim..lci.57, -5-5-6-5.
V A N C E , R . D . ,O C K E R M A N , H . W . , C A H I L L , V . R . & P L I M P T O N ,R . F . ,
1970.Carcasscompositionas relatedto meat sawdustanalysis.J. Anim.
. S c l 3. l , 1 9 2( A b s t r . ) .
W I L L I A M S , D . G . , T O P E L , D . G . & V E T T E R , R . L . 1 9 7 4 .E v a l u a t i o no f a
tissue-sawdust
techniquefor predictingbeef carc&sscomposition. J. Anim.
S c l .3 9 , 8 4 9 - E 5 4 .
Effect of shelter on the performance of
Friesian cows during winter in a
mediterranean climate
C.J.C.Muller*and J.A.Botha
Institute,PrivateBag Xl,
ElsenburgAgricultural
Development
Elsenburg,7607Republicof SouthAfrica
I3 April 1995
Received
5 September
1994;rcvised
22 Februun1995:uccepted
The ef'fectof differentshelters,that is, a shadestructure(3.-5m high)
in a dry lot and a tie-stallbarn in comparisonto a dry lot with no protection againstclimatic conditions(rain and wind), on the milk production and some physiologicalparametersof Dutch-typeFriesian
S.Afi.Tydskr.
I 995.25(2)
Veek..
cows was determinedover 53 days during winter in a temperateclimatezone.A completediet ( l3.5VoCP and 9.6 MJ ME/kg DM) was
fed ad libitum daily to cows. Ambient temperaturesrecordedduring
the trial were within the thermoneutralzone for dairy cattle (18.-5r
4.0 and 8.7 t 2.6"C for maximum and minimum temperatures
respectively).Total rainfall during the trial period was 180.6 mm.
Daily precipitationhigher than 5.0 mm was recordedon l2 days.
Although dry matterintakediffered (P < 0.01) betweentreatments,it
was not relatedto treatment.Daily milk productionand milk compositiondid not differ (P > 0.05) betweentreatments.
Plasmacortisol
and thyroxine levels of cows in the different housing systemsalso
did not differ (P > 0.0-5),
indicatingno advantage
in providingelaboratehousingfacilitiesfor dairy cowsundertheseclimaticconditions.
'n
Die invloedvan verskillendebeskuttingsfasiliteite,
naamlik ska'n
'n
duwee-afdak(3.5 m hoog) in
oop kamp en
intensiewebehui'n
singstelselin vergelykingmet
oop kamp waarin geen beskutting
(re€n en wind) verskaf is nie, op die melkteen klimaatstoestande
produksie en sekere fisiologiese maatstawwevan Hollandse tipe
Frieskoeieis oor'n periodevan 53 dae gedurendedie winter in'n
gebiedmet 'n gematigdeklimaatbepaal.'n Volledigedieet (13.5%
RP en 9.6 MJ ME/kg DM) is op 'n ad libitum-basisdaagliks aan
koeievoorsien.Omgewingstemperature
gedurendedie proetperiode
was binnedie gemaklikheidsone
vir melkkoeie(18.-5+ 4.0 en 8.7 +
2.6"C vir maksimumen minimum temperature
onderskeidelik).
Die
totalehoeveelheid
reenvalgedurendedie periodewas 180.6mm. 'n
Daaglikseneerslagvan hoer as 5.0 mm is op 12 dae aangeteken.
Hoewel daagliksedro€materiaal-innames
tussenbehandelingsverskil het (P < 0.01),kan dit nie aandie behandelings
toegeskryfword
nie. Melkproduksieen melksamestellingvan koeie binne die drie
behuisingstelsels
het nie verskil nie (P > 0.05). Bloedplasmapeile
van kortisol en tiroksienhet ook nie tussendie behandelingsverskil
nie (P > 0.0-5).
Resultate
dui op geenvoordelein die voorsieningvan
uitgebreidebehuisingsfasiliteite
vir melkkoeie onder hierdie klimaatstoestande
nie.
Keywords: Milk production,dry lot, tie-stall barn, shade structure, tyroxine,cortisol,temperate climate.
* To whom correspondence
shouldbe addressed
Various factors such as climate, herd size, cost, management
style and tradition influence dairy housing facilities (I arson,
1978).Although climatic conditionsin South Africa during winter are relatively mild, dairy farmers are becoming increasingly
more concerned about the negative ef'fects of adverse climatic
conditions that do occur and are therefore considering different
sheltering facilities. In the Western Cape dairy cows are kept
under zero grazingconditions in open camps (dry lots) with f-eed
being provided to them on a daily basis.This area has a temperate climate with hot, dry summersand cool, wet winters. Almost
60Vo of the annual rainfall occurs during the winter (May to
August). Wind and rain are significant components determining
the coldness of an environment. The insulative value of an animal's hair coat is reducedby wind and rain while the surfaceheat
exchangeis increased(Webster,1981).No information concerning the effect of various shelterson the milk yield of dairy cows
is available in South Africa. A study was therefore conducted to
determine the effect of providing protection during winter on the
production performanceof Friesian cows. Physiological parameters such as blood serum concentrationsof thyroxine (To) and
cortisol were also determined to evaluate the physiological
responsesto protection of cows during winter.