Fish Nutrition and Feeding

Fish Nutrition and Feeding LaDon Swann Mississippi-Alabama Sea Grant Consortium Auburn University Carcass Characteristics of Various Food Animals Characteristic of Carcass Source Dress Out (%) 60 61 72 72 Refuse (%) 14 15 21 30 Lean (%) 81 60 54 65 Fat (%) 5 25 26 9 Food Energy (kcal/100 g of edible tissue) 112 147 147 115 Channel Catfish Beef Pork Chicken Nutritional Comparisons of Various Proteins Nutrient Requirements • Energy requirements are lower for fish. • Fish require some lipids such as omega-3’s that warm-blooded animals do not. • Fish can absorb some minerals from water through the gills. • Most fish can’t synthesize ascorbic acid (Vitamin C). Fish Diversity • Because there are so many fish species, extreme variation in fish digestive systems exist among the families. Types of GI Tract • Herbivores – small stomachs and long intestine • tilapia • carp (stomach is 3X body length) • Omnivores – moderate size stomach and intestine • catfish • Carnivores – large stomach and short intestine • trout • striped bass Terms • Bioenergetics: Study of the balance between energy intake in the form of food and the energy utilization by animals • 1 Calorie: energy required to raise 1 g of water 1 C • Kilocalorie (kcal): 1,000 calories • Mega Kilocalorie: 10,000 calories More Terms • Intake Energy (IE): gross energy content of food source • Digestible Energy (DI): difference between gross energy and energy available to animals • Fecal Energy (FE): energy lost through feces • Urine Energy (UE): energy lost through urine • Gill Energy (ZI): energy lost through the gills Even More Terms • Metabolizable Energy (ME): difference between DE and energy lost through the FE + UE + ZI • Heat Increment (HI): rise in energy expenditure associated with the assimilation of ingested food • Maintenance Energy: voluntary activity plus basal metabolism – Feeds are based on satisfying maintenance energy PLUS enough nutrition for growth Gross Energy Values • Carbohydrates (Glucose) – 3.77 kcal/g • Proteins (Casein) – 5.84 kcal/g • Fat (Soybean oil) – 9.28 kcal/g Digestible Energy Feedstuff Anchovy Meal Soybean Meal Wheat middlings DE/IE 0.91 0.79 0.40 ME/DE 0.94 0.94 0.91 Conversion Efficiency • Fish require less energy for protein synthesis. – catfish, 0.84 g gain/g food consumed – chickens, 0.48 g gain/g food consumed – Beef, 0.13 g gain/g food consumed • Fish are better at assimilating high protein diets. • Fish poorly utilize carbohydrates for energy. Conversion Efficiency • Lower energy cost for protein gain – Fish 47 g/MKcal ME – Chicken 23 g/MKcal ME – Beef 6 g/MKcal ME • Protein fed to protein gain is similar among fish, birds, and mammals – Fish, 0.36 g protein gain/g protein fed – Chicken, 0.33 g protein gain/g protein fed – Beef, 0.15 g protein gain/g protein fed Fate of Nitrogen and Phosphorus in Feed Retained in Tissues 30% N 32% P Food 100% N 100% P Solids 13% N 60-90% P Effluent 70% N 68% P Dissolved 87% N 10-40% P Comparison of Feed and Dietary Protein and Energy Among Common Livestock Feed Composition P (%) Energy (kcal ME/g) MEprotein ratio (kcal/g) 8.5 16 24 Wt. Gain/g of diet Efficiency Protein gain/g protein consumed 0.36 0.33 0.15 Protein gain/ Mkcal ME consumed (g) Animal Channel Catfish Broiler Chicken Beef Cattle 32 18 11 2.7 2.8 2.6 0.84 0.48 0.13 47 23 6 Bioenergetics • Digestible Energy (DE) % DE = IE - FE IE • Metabolizable Energy (ME) IE – (FE - UI - ZI) % ME = IE – Approximately 85% of nitrogenous wastes pass through gills Heat Increment • Heat Increment (HI) of ME is 3-5% in fish vs. up to 30% in mammals. • Lower HI is due to the ammonia excretion rather than urea or uric acid. – 1 ATP / N in Ammonia – 4 ATP / molecule of Urea (2 Nitrogen) – 10 ATP/4 N in Uric acid Fish Have Lower Maintenance Requirement • Lower Maintenance Energy – Rainbow Trout • Maintenance Energy = 57kcal/kg bwt to the 0.63 power – Mammals • Maintenance Energy = 70-83 kcal/kg bwt to the 0.75 power Why Lower Energy Requirement? • Don’t have to maintain body temperature (HI) • Less energy to maintain position • Lose less energy in protein catabolism and excretion of nitrogen Carbohydrates • Fish have poor control over glucose levels. – Following glucose ingestion, blood glucose levels rise rapidly, but may take hours to decrease. – Turnover of glucose in trout is 10X slower than in rats. Proteins Requirements • Fingerlings require higher protein than finished fish. – 3 g cc (27%) required 4X more than 250 g cc (38%) – based on a diet low in energy – high energy diet: consumption decreased and 27% wasn’t enough Protein and Digestible Energy Requirements by Sizes of Channel Catfish for Protein Synthesis Size (g) Protein (g/100 g fish /day) DE (kcal/100 g fish/day) DE/Protein ratio (kcal/g) 3 10 56 198 266 1.64 1.11 0.79 0.52 0.43 16.8 11.4 9.0 6.1 5.0 10.2 10.3 11.4 11.7 11.6 Catfish Feed (Floating) Guaranteed Analysis Crude protein not less than Crude fat not less than Crude fiber not more than 32.0% 3.5% 7.0% Ingredients Soybean meal, ground yellow corn, fish meal, brewers' dried yeast, wheat middlings, animal fat preserved with BHA, vitamin A supplement, vitamin B supplement, D-activated animal sterol (source of vitamin D ), DL-methionine, calcium pantothenate, folic acid, niacin supplement, riboflavin supplement, menadione sodium bisulfite (source of vitamin K activity), ascorbic acid, salt, calcium carbonate, ferrous carbonate, manganous oxide, calcium iodate, copper sulfate, cobalt carbonate, zinc sulfate. Feed Formulation • • • • • Cost of ingredients Nutrient content of ingredients Nutrient requirements Nutrient availability Min.-Max. restrictions of ingredients Typical Catfish Diet Containing Fishmeal • • • • • • • • • • Menhaden fishmeal Soybean meal (48% P) Corn (ground) Rice bran or wheat Dicalcium phosphate Organic binder Fat (sprayed) Trace minerals Vitamin mix Ascorbic acid 8.0 48.2 29.2 10.0 1.0 1.5 0.05 0.05 0.05 0.038 Types of Fish Feed • Live – Algae – Zooplankton – By-catch/trash fish • Formulated – Floating – Sinking – Mixed Sinking Extruded (Floating) Feeding Rates • Animals must be fed often enough to satisfy maintenance requirements plus planned growth. • Feeding methods – Percent Body Weight • Percent to feed: range from 1-10% per day • Growth Rate • Biomass to feed – Satiation Feeding • Feed as much as the animals will eat in 15-30 minutes Feeding Frequency • Types of GI Tracts – Herbivores => Omnivores => Carnivores • Size of Animal – Larvae => Juveniles => Adults => Broodstock • Frequency – 1-10 times per day