Fish nutrition

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Fish nutrition

  1. 1. Fish Nutrition Fish nutrition and feed rates Nutrition affects GROWTH RATES
  2. 2. Fish Nutrition Important component for whole production system Target species production Growth, FCR, Water Quality, Disease Economics Overfeed and Underfeed Species specific formulations available Pond production Closed recirculations systems (such as aquaponics)
  3. 3. Intensive Fish Production
  4. 4. Why feed fish? Intensification reduces natural food organisms inpond Some culture methods have little chance of naturalfood sources Aquaponics, cages, raceways Reduce reliance on natural foods Have control of what fish eats
  5. 5. Essential Ingredients Protein Fat Carbohydrate Minerals Vitamins
  6. 6. Protein Composed of amino acids Ten can be synthesized by vertebrates, including fish Essential: Must supply = protein quality Important component in diet Expensive Small quantity of good protein produces large amount of fingerlings Used for FISH GROWTH A fish does not have a minimum protein requirement; it has aminimum amino acid requirement Nutritionist should know AA composition and digestibility Poor quality protein is burned for energy or deposited as fat
  7. 7. Factors Affecting ProteinRequirement Size of fish: Small fish require more protein than largerfish Protein quality: Protein needs to be of good quality(such as from grain amaranth or black soldier flylarvae) Natural foods: Some fish use natural foods effectively. Depends on stocking density
  8. 8. Factors Affecting ProteinRequirement Protein: Energy Ratio: If energy level of diet low, you will waste protein to meetmetabolic needs. Inefficient and expensive. If protein level low and energy moderate, then fish willget fat. If energy level too high, it suppresses food intake andfish don’t meet protein requirement. Results in lowgrowth rate over time and undersized fish.
  9. 9. Typical Protein Requirements ForTilapiaFirst feeding fry 45-50%0.02-2.0 g 40%2.0-35.0 g 35%35.0 g - Harvest 30-32%
  10. 10. Protein Sources Animal protein Fish meal Balance of amino acids that approach requirements of most fish Palatable and digestible Not sustainable Trash fish By-catches High water content, spoils Anti-nutritional enzymes Not sustainable Poultry Plenty of product due to chicken farming Nutrition depends on part of chicken Warrants more experiments Insects High in protein (e.g. Black soldier fly larvae) High in water content Availability, production cost Diet supplement Crustaceans High in protein High in chitin Zooplankton Fed in combination with commercial diet Usually not sole source of feed because readily take dry feed
  11. 11. Protein sources Plant Protein Usually lacks in AA content Must add additional AA Many contain anti-nutritional factors and/or toxins Deactivated or destroyed by soaking or heat Soybean (30-50%) Farmed all over Amino acid imbalance Inclusion of other ingredients Palatability Attractants Trypsin inhibitor Heated during processing Partial replacement probable
  12. 12. Protein Sources Cottonseed Meal (20%) Contains toxin gossypol Direct and indirect effects of gossypol Direct Liver Indirect Binding to AA Binds to lysine making itneutral, supplemental lysineneeded Palatable, economical in areas ofUS that produce cotton Glandless cotton contains nogossypol. Difficult to find in US Rice (<75% inclusion) Nutrient value limiting Algae (10-20%) Production expensive Dry meals are expensive Best ‘in situ’. Some are toxic High in carotenoids Duckweed (<20%) Very common in ponds High in water Dietary supplement
  13. 13. Lipids Source of energy and essential fatty acids One gram of lipid contains 2x the energy of 1 gramcarbohydrates or 1 gram protein Spare the protein for growth Maintain cell fluidity Globular proteins transport things in and out of the cellmembrane
  14. 14. Lipids Dietary lipids Provide HUFAs for good growth and reproduction Cannot be synthesized, must supply the basic ones Oleic acid Linoleic acid Ecosapentenoic acid Docasahexaenoic acid Arachodonic acid tilapia
  15. 15. Energy-Why does a fish need it? Energy is not a food stuff Formed from breakdown of feed Protein, lipids and carbohydrates Activity Chemical reactions Nervous system Osmoregulation Growth Energy reserves Excretion of wastes Reproduction
  16. 16. Energy Fish eat to satisfy their energy demands Too much energy Get fat or do not satisfy their protein requirement = don’tgrow Too little energy Utilize protein as energy source = $ costly Require less energy than land mammals Cold-blooded Live in water Waste excretion
  17. 17. Factors Altering EnergyRequirements of Fish Species Warmwater/Coldwater Herbivores/Carnivores Water Temperature Fish are poikilothermic Metabolic rate directly related to water temperature Rise of ten degrees doubles rate of metabolism Fish Size Smaller fish Developing muscle, bones, organs, growth Larger fish Slower growth and basal metabolism
  18. 18. Factors Altering EnergyRequirements Of Fish Fish Age Energy requirement decreases as age increases Physiological Activity Spawning activity and formation of reproductive systems Environmental Factors Water current Swimming and positioning Water quality Diet Composition Fry/broodfish High protein and fats
  19. 19. Carbohydrates Fish do not have access to food with muchcarbohydrate; mostly protein and fats Limited digestibility (35-80%) Not much research done on carbohydrate Wheatgerm=lipid, protein Endosperm = starch Bran = protein Breakdown of glycogen to glucose Used in cellular metabolism
  20. 20. Minerals Inorganic elements Not much known Inexpensive to add: premixes Fish can obtain some from the water Two groups Major minerals Ca, P, Mg, Na, K, Cl, S Trace minerals Nothing to do with importance Fe, I, Mn, Cu, Co, Zn, Se, Al
  21. 21. Minerals Calcium Bones and scales Muscle function, blood clotting, osmoregulation 98% of Ca in form of bones, teeth, scales, spines Phosphorus Bones, nucleic acids, enzyme systems Hard to find in water; tied up in muds Osmoregulation Maintain constant osmotic pressure with body fluids Sodium Extracellular cation Chloride Extracellular cation Potassium Intracellular cation
  22. 22. Vitamins Essential but don’t supply energy Normal metabolism Must supply because cannot be synthesized at all or fast enough Two groups Water soluble Deficiency common Vitamin C Fish cannot synthesize Fat soluble Deficiency rare Vitamin A=mucous secretion Vitamin D=Calcium/phosphorus adsorbtion
  23. 23. Feed Preparation Steam pelleting Produces dense pellet that sinks in water Extrusion process Produces floating pellet Good for feeding behaviour observation Holds together well in water Fines Small feed particles that deteriorate water quality (< 1%)
  24. 24. Artificial Diets Complete Diet Provides ‘all’ essential ingredients for species growth Required in: Semi-intensive to intensive systems Closed Recirculation Systems Cage Reproduction Temperate Climates Short growing season Aquaponics Greenwater
  25. 25. Artificial Diets Supplemental Diets Incomplete diets intended to bolster natural production Lack required levels of essential ingredients Extensive Production Systems
  26. 26. Feed Rates Dependent on: Management strategy Feed type and size Species size and density Water temperature and quality Weather
  27. 27. Feeding Strategies Ad libitum or Satiation Feed all fish will eat during timed period 2-4x/day Farmer understands his/her ‘fish personalities’ Percent Body Weight/Day Based on growth rate, FCR, and survival Requires frequent sampling Divide daily ration; fed 2-4x/day
  28. 28. Feed Conversion Ratio (FCR) How much feed is converted to fish flesh? FCR <1.5=doing well 1.5=average 1.5-2.0=fair >2.0=something’s up Calculated as: FCR=Amount of feed fedFish weight gain Example: FCR = 50 kg = 1.730 kg
  29. 29. Feed Presentation Hand feeding Advantages Fish behavior observation by feeders detecting problems at source Healthy, vigorous feeding and only just enough fed at any onetime since humans can detect when fish have had enough Disadvantages Labor intensive Demand feeder Advantages Ad libitum, less labor Disadvantages Nature, higher FCR, fish bullies eat more than others, frequentlybreaks and fouls water causing mass fish die-off, capital costs
  30. 30. Types of fish pellets Sinking Must be fed slower Hard to observe fish behavior Floating Has air pockets Easier to observe fish behavior
  31. 31. Size of Fish Feed Very important Fish will not consume Water quality issues Economics Increase in energyrequirements wheneating wrong size Mixing two feed typesimportant during feedsize transition1• Feed size #12• Feed size # 1 mixed with• Feed size #23• Feed size # 2
  32. 32. Feed ChartSize of fish/fry Feed Type % Body WeightYolk absorb to 1.5 g Methyl TestosteroneFeed Powder25-15%1.5-5 g Fry Starter 200 (Powder) 10%5-20 g Rangen Extra 450 (1/16”) 6%20-50 g 5DO8 (3/32”) 3%50-700 g 5DO7 (1/4”) 3-1%
  33. 33. Feeding Protocol Tilapia have a modified stomach At UVI we found 3 feedings each day Divide daily ration up accordingly Ad lib accordingly (hand feed and observe fish behaviorfor signs of trouble and bullying)
  34. 34. Feeding Protocol Reduce feedings if temperature not optimum Optimum temperature is 23-31°C Oxygen > 5 ppm for feeding tables < 3 ppm do not feed Lowest oxygen reading can be just after feeding Feeding response-watch fish behavior for feeding/notfeeding/bullying/sateity. When fish stop eating, STOPFEEDING High solids or organics (ROTTEN FEED LEFT OVER INTANK or filtration failure) Water quality (high ammonia/nitrites = fish notfeeding, gasping at surface, emergency)
  35. 35. Feed Fish Properly Water quality closely controlled High growth rate and low FCR Uniform Bullies/runts eliminated Dress-out even weight Nutrition-linked diseases eliminated Scoliosis, cataracts, fat deposits, etc
  36. 36. Feed Fish Improperly Poor water quality High levels of ammonia, nitrite, wrong pH, lowdissolved oxygen Slow growth and high FCR Nutrition-linked diseases prevalent Less uniformity Size variation Dress-out percentage low
  37. 37. Feed Storage Inadequate storage leads to nutrient loss Sunlight = vitamin loss Heat = rancid fats Damp = molds Cool, dry place Air-conditioned room Use before expiration date (3 months) Don’t stack higher than 10 on pallet First in, first out strategy Rodent resistant Rodents eat feed and defecate on it, introducing pathogens.
  38. 38. Recommended Reading Chhorn Lim and Carl D. Webster, 2006 Tilapia: Biology, Culture, and Nutrition Chhorn Lim and Carl D. Webse,r 2002 Nutrient Requirements and Feeding of Finfish for Aquaculture Kim Jauncey, 1988 Tilapia feeds and feeding.This information courtesy Jason Danaher, UVI withminor embellishments Charlotte Appleton, World TreeSolutions.

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