What do the Experts Say
about Replacing Fish in
Fish Food
History of Fish Diets
The original extruded fish diets were primarily soy
Based. Soy based diets extrude very well and fish
grew.
PROBLEMS:
Fish didn’t taste much like their wild counter parts
Water Quality
Feed Efficiency
BASIC NUTRITION
“Series of processes by which an
organism takes in and assimilates
food for maintenance, growth,
production and reproduction”
NUTRIENT
“Chemical element or compound that
is required in the diet of a given
animal to permit normal functioning:
CLASSES OF NUTRIENTS:
Amino Acids
Carbohydrates
Fatty Acids
Vitamins
Minerals
CARBOHYDRATES
Various combinations of carbon and water
•NFE:
–Sugars
–Starches - amylose, glycogen
•Fiber:
–Structural - hemicellulose, cellulose, lignin
•Plants:
–Energy storage and structure
•Animals:
–Metabolic fuel - available energy
FAT
Combination of C, H, and O
•Triglycerides - three fatty acids esterified to a glycerol
•Certain fatty acids are essential
•Other lipids
•Most concentrated form of energy storage
•Long-term energy storage in animals
PROTEINS
Combination of C, H, O and N
•Made of many amino acids linked end to end
•Animals’ structure ad function:
Scales, skin
Hemoglobin, insulin, actin & myosin
•No protein requirement, per se
Dietary Protein
Most expensive component of diet
Protein quality (not quantity)most important
Historically Fish Meal has been best – fish
protein to grow fish
100s of scientific papers on the “replacement
value” for a protein source – always
compare to fish meal as the gold standard
DIGESTION
Small Intestine - Enzymatic
Degradation
•Carbohydrates:
Amylases, Lactase, Sucrase
•Fats:
Bile Salts, Lipases
•Proteins:
Proteases, Trypsin, Chymotrypsin, Peptidases
DIGESTION
Consumed
Absorbed*
Carbohydrates…………………………Simple Sugars
Fats…………………………………….Fatty acids, glycerol
Proteins………………………………..Amino acids
*Absorbed into blood or lymph
GI TRACT
Reflects an animal’s eating
habits
•Complexity
•Length
Digestion and Absorption
• What about fiber? Plants contain fiber.
• FISH
•No foregut fermentation
•Little or no hindgut fermentation
•Mastication/grinding
–Carp - pharyngeal teeth
–Milkfish, gizzard shad - gizzard
–Grass Carp
Fish
• Efficiency of converting food into meat or eggs
FCR (feed conversion ratio; units = g food per g gain
–Cattle = 6-8
–Hogs = 3
–Chickens = 2-3
–Fish = 1-1.5
These efficiencies are under
optimal conditions, and will
drop with underfeeding or
overfeeding!
GI Tract
– Land Animals
»Sheep 35:1, Ruminants
»Pigs
14:1, sacculation
»Cats
4:1, simple
Terrestrial Animal
Stevens and Hume, 1996
GIZZARD SHAD
>5 x B.L.
Bluegill:
B.L.
G.I.T.
G.I.T.:BL
=
=
=
20 cm
24 cm
1.2
Fish Diets
Why are fish so efficient?
-Fish have reduced energy requirements
- Cold blooded (poikilothermic)
- energy not needed to maintain body T
- Aquatic
- not fighting gravity
- able to excrete nitrogen more easily
- Generally utilize readily available nutrients
- e.g., unlike a cow that needs microbial
digestion to use it’s food
FISH vs. TERRESTRIAL ANIMALS
Carbohydrate Utilization
•Little amylase activity = varies
–Warm vs. Cold water species
–Fresh vs. Salt water species
•Cooked vs. Raw starch
•Aquatic vs. Terrestrial Carbohydrate
Carnivorous & Omnivorous
• Carnivorous: Trout, Bass, Perch,
Walleye, Bluegill
– All Starting fish
– Protein-based diets
• Omnivorous: Catfish, Carp, Koi, Tilapia
– Can utilize some carbohydrates
Effect of replacing dietary fish oil with
Soy Oil in cobia
• SO can replace a substantial amount of FO in aqua
feeds.
• Production performance is largely unaffected by
partial replacement of FO with SO
• FA composition is significantly altered, even at
low levels of FO substitution.
• Aggressive FO replacement may result in
development of EFA deficiency, particularly in
reduced-fish meal Formulations.
Fisheries and Illinois Aquaculture Center, Southern Illinois University Carbondale, Carbondale, IL; 2 Virginia Seafood
Agricultural Research and Extension Center, Virginia Tech, Hampton, VA; 3 International Initiative for Sustainable and
Biosecure Aquafarming, Norfolk, VA, USA; 4 Marine Fish Culture Laboratory, Institute of Oceanography, Federal University
of Rio Grande, Rio Grande, RS, Brazil
Effects of replacing fish meal with SPI on growth
and nutrient utilization in Rainbow Trout
• Soy protein concentrate can replace 50% of the
fish meal in high-lipid, extruded diets for rainbow
trout without reducing performance..
• Replacing 75 or 100% of the fish meal with soy
protein may reduce growth because of lower feed
intake and low lipid digestibility.
M Mambrini, A J Roem, J P Carvèdi, J P Lallès and S J Kaushik
Insect-based fish feed for rainbow trout
Black soldier fly (Hermetia illucens)
Sophie St-Hilaire1, Wendy Sealey2, Mark
A. McGuire2Jeffery Tomberlin3, Craig
Sheppard4, Larry Newton4,
MirielleChahine2, Mario De HaroMarti 2,
and Carolyn Ross 5
1Idaho State University2University of Idaho
3Texas A &M University 4University of
Georgia5 Washington State University
Insect-based fish feed for rainbow trout
• Black soldier fly (Hermetia illucens)
• Between 20 and 50% reduction in phosphorus
and nitrogen in remaining material
• Pupae by-product is a suitable animal grade
foodstuff ~40% protein ~30% fat
Insect-based fish feed for rainbow
trout
Control
diet
Weight
2054a
gain (g)
Feed
Conversion
Ratio *
1.18a
25%
fishmeal
25%
replacement
fishmeal
replacement
50%
fishmeal
replacement
1815a,b
1559b
1.22a
1.47b
Change
-25%
-20%
Human Health and Nutrition
• American Heart Association recommends the consumption
of oily fish at least twice a week1
• Omega-3 content of farmed fish depends on the FO levels
in fish diets2
• Determines health benefits of seafood consumption
• Example: consumption of salmon raised on the high-FO
diet reduced triglycerides and improved other health
indicators of patients with coronary heart disease
• These effects were not significant in patients consuming
salmon raised on low-FO diets2
1Lichtenstein
et al. 2006, 2Seierstad et al. 2005
Reducing fish meal and fish oil
inputs in feed
• Feed is the largest production cost for commercial
aquaculture thus improving feed efficiency in
industrial systems is already a priority
• Research to develop substitutes for FM & FO is
now focused on commodities such as oilseeds
(especially soybeans), meat byproducts (such as
blood meal and bone meal) and microbial protein
• complete replacement of fish meal and fish oil in
aquaculture feeds faces severe barriers
Fish Meal Replacement: AquaMax
4.5
• Primary goal - to replace FM and
FO in fish diets
4.0
• 33 partners, 14 countries
• Four years of research and $21.6
MM
• Replacement of FM with a
mixture of corn gluten, wheat
gluten, soy concentrate, krill
meal, and amino acids resulted in
17% weight reduction of fish
Torstensen et al., 2008
Salmon weight (kg)
3.5
a
b
b
3.0
2.5
2.0
1.5
1.0
0.5
0.0
30% FM + 6.5% FO 12% FM + 16% FO
12% FM + 7% FO
*Bars not sharing a common letter are significantly
different (P < 0.05)
Questions