NUTRITION, FEEDS AND FEEDING

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NUTRITION, FEEDS AND FEEDING

• Digestive process in fishes
• Organs involved function
• Nutritional requirements
• Feed processing/characteristics
• Energy budgets
• Feeding regimes/rates

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AILIMENTARY TRACK

• Oral Cavity - Mouth, Teeth
• Esophagus
• Stomach - Cardiac and Pyloric
• Intestine Small, large and rectum

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Digestive Organs - Liver

• LIVER - Process and storage of lipids and
  carbohydrates, production of plasma proteins
• Formation of bile

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Gall Bladder

• Stores bile and secretes into gut
• Bilirubin (yellow color) oxidizes to biliverdin
  (blue-green) over time

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Digestive Organs- Pancreas

• Exocrine
• Scattered islands of secretory tissue in
  mesentery pyloric caeca
• Endocrine - Islets of Langerhans
• Insulin and glucagon production for carbohydrate,
  fat and protein metabolism

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Classifications of fish species

• Coldwater Carnivores
• Coolwater Carnivores or omnivores
• Warmwater Herbivores or omnivores
• Feed must meet specific dietary requirements

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NUTRITION, METABOLISM AND GROWTH

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Proximate analysis

• Feed formulated based on analysis of individual
  ingredients
• Moisture
• Ether extract fat soluble vitamins, carotene,
  chlorophyll, sterols, waxes, fats and fatty acids
• Ash
• Crude fiber low digestible plant carbohydrates
• Nitrogen-free extract (NFE) consists mainly of
  digestible carbohydrates

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PROTEIN

• 30-50 in most fish diets
• IMPORTANT FOR FISH structure/muscle, gonads and
  growth
• Proteins
• Linear relationship between daily protein and
  growth
• Utilization of protein relatively constant and
  independent of feeding - (carnivore, omnivore,
  herbivore)

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CARBOHYDRATES

• Not very important for most fish species
• Appear as sugars and starches
• Trout have limited ability to digest
  sugars/starches
• May affect fish health
• Catfish digest starch well

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CARBOHYDRATES

• Fish lack the enzyme cellulase
• Unable to break down cellulose
• Fiber usually considered to have 0 nutritional
  value
• Cellulose often used as binding agent
• Levels of 10 to 20 have resulted in growth
  depression in rainbow trout
• Catfish?

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LIPIDS

• Lipids for energy, structure and function of
  _____________
• Fish utilize lipids with low melting points (Pu
  fa) - polyunsaturated fatty acids
• Typically supplied in diets from 7-16

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ESSENTIAL FATTY ACIDS

• Triglycerides with polyunsaturated fatty acids
• w 3 and w 6 - Omega or linolenic series (n-
  series) of fatty acids
• Digestibility of lipids is 85-95
• Major source is fish oil (salmonids) or soybean
  oil (ictalurids)

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MINERALS

• Required by all animals fish can uptake some
  from water
• Formation of skeletal tissue
• Respiration
• Digestion
• Osmoregulation (SW high minerals/salts, FW
  low
• Major minerals
• Ca, Phos, Sulphur, sodium, chloride ion, K,
  Magnesium
• Trace minerals
• Cobalt, Copper, Fluorine, Iodine, Iron,
  Manganese, etc.

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MINERALS

• Dietary Phosphorus
• Phosphorus reduction
• Increase plant protein
• High in phytate phosphorus

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VITAMINS

• COMPLEX SUBSTANCES
• FAT SOLUBLE VITAMINS
• A- Retinol - carotenoids converted in intestinal
  mucosa
• E - Tocopherol - antioxidants in fish diets
• K - Two forms in green plants - blood clotting
  and bacteriostatic
• D - calciferols not well understood

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WATER SOLUBLE VITAMINS

• B1 - coenzyme of carbohydrate metab
• digestion, reproduction, nervous system
• B2 - Riboflavin- eyes function, cataracts
• B6 - Pyridoxin
• Pantothenic acid
• Lamellar hyperplasia
• Inositol - reduced growth rates

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WATER SOLUBLE VITAMINS

• Niacin - haemorrhage erosion epidermis
• Biotin - can cause darkening anorexia
• Choline -poor growth and conversion
• Cyanocobalamic (B12)- anemia
• Folic acid - haemopoiesis - erythrocytic anemia

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WATER SOLUBLE VITAMINS

• Ascorbic Acid (C)
• Important - Collagen skeletal systems
• Wound healing, disease resistance
• Fish and primates can not synthesize

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Other dietary factors

• Attractants
• Attract fish by sight or smell (shrimp meal, fish
  oil, fish meal, etc.)
• Pigments
• External
• Crayfish, red snapper, koi, etc.
• Flesh color pink in salmon or trout
• Must be obtained from feed (crustaceans, yeast,
  plants/algae)

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Other dietary factors

• Behavior
• How a feed particle moves through water column
• Mimic natural food

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Practical diets

• Dry feeds
• Made from all dry ingredients with addition of
  liquid fat (fish or oilseed oil)
• Pellets, crumbles, or flakes
• Floating or sinking feeds of various size
  designations

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Practical diets

• Pellets
• Feed ingredients mixed and forced under pressure
  through different size dies
• Stability varies depending on binders used

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Practical diets

• Microencapsulated small particles of uniform
  nutritional make up
• Slurry of fine ground ingredients
• Encased in proteinaceous membrane (microcapsule)
• Expensive, but used for some species (larval
  marine)
• Moist and Semi-moist feeds (OMP 32 moisture)
• Formulated with high of whole fish
• Stored frozen

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Practical diets

• Extruded feeds/pellets
• Mixed ingredients passed through extruder barrel
• Floating, slow sinking, and stable pellet
• Increase lipid content (energy) by spraying
  extruded feeds after process
• Enhanced digestibility of some ingredients