Fish Feed as Nutrition for Fish and Plants
Kevin Fitzsimmons, Ph.D.Sec. Tres. American Tilapia Association
Past President – World Aquaculture Society
Professor, University of Arizona
Aquaponics12 April 2012
Contents
Nutrition Ingredients and Formulations Manufacture and Preparation Storage, Handling, and Feeding Methods
Nutrition and feeding behaviours Tilapia are omnivores (eat lots of things) Especially capable of consuming decaying
vegetable matter Long intestine Filter feeders (algae, bacteria, plankton) when
young Need protein and balanced nutrition for rapid
growth Maybe more cost effective to settle for moderate
growth
Feeding strategy Juvenile fish are especially good at filter
feeding phytoplankton.Many hatcheries utilize greenwater culture Juveniles also filter feed on small
zooplankters (especially crustaceans)Save money on juvenile feeds by partial
nutrition from natural feed in juvenile ponds and tanks
Tilapia nutrition decisionsNatural herbivores and detritivores. Opportunistic feeders grazing on algae and
bacteria in production system.Fry and fingerlings need high protein
(50-40%) dietGrowout needs lower protein (32-28%) diet“Organic” diets may be needed for “organic”
buyersCompare FCR to decide most efficient diet
Minimize fish meal in diet
Use more soybean meal Utilize other grains treated with phytase Increase use of other by-product meals
(meat and bone, blood, feather, poultry by-product, brewers waste, etc.)
Examine other locally available ingredients (rice bran, cassava leaf meal, etc)
Long convoluted intestine.Digests complex organic matterFry are filter feedersAdults are grazers
Tilapia Biology
Proteins
Tilapia need balanced set of amino acids. Basic building blocks of proteins (and muscles)
Ten essential amino acids (required) several more are supplemental
Lipids
Lipids are basically fats. Fish need a variety of long chain
hydrocarbon fatty acids for proper growth Tilapia will also bio-accumulate lipids from
consumed algae
Remember organic chem?
Found in many freshwater and marine algae, canola, walnuts, soybean, and flaxseeds
Essential part of the nutritional requirement of almost all organisms
Important in neural and cardiovascular functions
Facts about fatty acids in other farmed fish
Fatty acids can also be elevated in fish depending on feed ingredients
Higher omega-3’s are expensive and will likely require higher price
Tilapia - Moderate in PUFA’s: 0.387 g/100g raw
0.600 g/100g cooked Tilapia - Moderate omega 3 FA’s:
0.141 g/100g raw0.220 g/100g cooked
Source – USDA- ARS Lab
Carbohydrates
Needed for metabolic energy Carbohydrates are polymers of sugar. Common ingredients are corn, sorghum,
rice Molasses is mostly sugar and water. Does
not supply as much energy as equal mass of lipid (fat)
Fiber
Less digestible material to help move material though the intestines.
Helps with micronutrients
Vitamins and minerals
Commonly supplied in “premix” Often available in natural production of
ponds. Not critical for most semi-intensive fish
farm operations. Very critical in intensive systems (cages,
raceways)
Pigments Salmon and trout feeds sometimes include ingredients
that impart reddish or pink color to the flesh. Astanxanthin, canthaxanthin and beta-carotene are
commonly used. These may be plant or algae extracts, or chemically
derived. May also use whole algae as ingredient (Spirulina or
Dunaliella) Yes, the same extracts and algae sold in health food
stores, (which was not included in the scare stories)
Binding agents
Gums, agar, cooked starches, wheat and corn glutens, and other ingredients can be used for binding.
Preservatives
Ethoxyquin Anti-oxidants
Goal is to avoid rancidity, loss of nutrients
Attractants
Fish oil, fish meal, and fish solubles are good attractants
Ingredients and formulations
Normally need high protein diets for young 40-50% Protein requirements drop as fish reach
reproductive age. Lipid demand might increase with egg formation. 30-32%
Growout diets only need 25% protein
Manufacturing and preparations
Pellet mill
Compression pellet mill
Feed mixed with water to dough consistency Moistened feed put into hopper, pushed down
to auger screw Auger forces feed through the die head. Holes in die determine pellet width Knife blade cuts pellets to desired length
Extruders
Floating feeds Feed mixes with steam in barrel of extruder Cooks ingredients, improves palatability Gelatinizes starches Steam expansion and auger forces feed out
of barrel with rapid expansion. Traps air in pellet, allows to float
Meat grinders and pasta mills
Bioflocs
Deliberate culture of high density of phytoplankton and bacteria
Storage
Always keep feed as dry and cool as possible Avoids spoilage and rancidity of fats in diet Bags should be on pallets, off floor to allow
air to circulate and slow pests (mice, rats, roaches, ants, from getting to bags
Large amount can be stored in bulk in silos.
Handling
Reduce rough handling Crushed pellets form fines which are not
consumed by fish. Fed by hand, blower, belts
Conclusions Tilapia are omnivores But eating anything will not make you grow
fast and strong Tilapia need balanced nutrition for rapid
growth just like human children
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