nutrition, feeds and feeding digestive process in fishes organs involved & function nutritional...
Post on 22-Dec-2015
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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
AILIMENTARY TRACK
• Oral Cavity - Mouth, Teeth
• Esophagus
• Stomach - Cardiac and Pyloric
• Intestine – Small, large and rectum
Digestive Organs - Liver
• LIVER - Process and storage of lipids and carbohydrates, production of plasma proteins
•
• Formation of bile
Gall Bladder
• Stores bile and secretes into gut –
• Bilirubin (yellow color) – oxidizes to biliverdin (blue-green) over time•
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
Classifications of fish species
Coldwater: Carnivores
Coolwater: Carnivores or omnivores
Warmwater: Herbivores or omnivores
• Feed must meet specific dietary requirements
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
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)
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 –
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?
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%
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)
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.
MINERALS
• Dietary Phosphorus– –
• Phosphorus reduction– – Increase plant protein
• High in phytate phosphorus
–
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
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
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
WATER SOLUBLE VITAMINS
• Ascorbic Acid (C) *– Important - Collagen skeletal systems– Wound healing, disease resistance– Fish and primates can not synthesize
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)
Other dietary factors
• Behavior– How a feed particle moves through water
column •
•
•
• Mimic natural food
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
Practical diets
• Pellets:– Feed ingredients mixed and forced under
pressure through different size dies
– Stability varies depending on binders used
–
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