Fish Nutrition


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Fish Nutrition

  1. 1. Aquaculture Nutrition
  2. 2. Feed Conversion Ratio <ul><li>The measure of an animals efficiency at converting pounds of food to pounds of body mass. </li></ul><ul><li>Examples: </li></ul><ul><ul><li>Cows 8:1, 8 lbs of food for 1 lb meat gain </li></ul></ul><ul><ul><li>Pigs 4:1 </li></ul></ul><ul><ul><li>Chickens 2:1 </li></ul></ul><ul><ul><li>Fish </li></ul></ul><ul><ul><ul><li>Tilapia 1.7:1 </li></ul></ul></ul><ul><ul><ul><li>Atlantic Salmon 1.2:1 </li></ul></ul></ul>
  3. 3. Fish Conversion Efficiency <ul><li>The basic principle in feeding is that the fish should be fed exactly to satiation. </li></ul><ul><li>Reasons for efficiency </li></ul><ul><ul><li>the biology of the fish, </li></ul></ul><ul><ul><li>the way the fish live and </li></ul></ul><ul><ul><li>the high nutrient concentration of fish feed. </li></ul></ul>
  4. 4. Nutrition <ul><li>Fish have a low body maintenance requirement. </li></ul><ul><ul><li>Fish are cold-blooded: </li></ul></ul><ul><ul><li>Floating in the water consumes less energy than standing and walking on legs. </li></ul></ul><ul><li>Fish feeds are also more concentrated than those for pigs or cattle, since they do not need ‘filler’ ingredients such as fiber. </li></ul><ul><li>Fish use oils and fats as their prime energy source - more concentrated than the carbohydrates needed by land-living animals. </li></ul><ul><li>Most fish are carnivorous while most farmed land animals are basically herbivorous </li></ul>
  5. 5. Nutrition <ul><li>Protein </li></ul><ul><ul><li>Balanced mix of amino acids builds muscle </li></ul></ul><ul><li>Fat </li></ul><ul><ul><li>Provides dense energy for metabolism </li></ul></ul><ul><ul><li>Oxidizes rapidly – becomes rancid </li></ul></ul><ul><li>Carbohydrate </li></ul><ul><ul><li>Fish can only digest simple sugars </li></ul></ul><ul><li>Vitamins & Minerals </li></ul><ul><ul><li>Included in mixed rations </li></ul></ul>
  6. 6. Food Storage <ul><li>Keep cool – slows oxidation </li></ul><ul><li>Keep dry – prevent mold growth </li></ul><ul><ul><li>Mold produce mycotoxins </li></ul></ul><ul><li>Keep covered </li></ul>
  7. 7. Water quality elements <ul><li>Oxygen </li></ul><ul><li>Temperature </li></ul><ul><li>Sunlight </li></ul><ul><li>pH </li></ul><ul><li>Alkalinity </li></ul><ul><li>Hardness </li></ul><ul><li>Ammonia </li></ul><ul><li>Nitrite </li></ul>
  8. 8. Oxygen <ul><li>Minimum: 4 ppm , </li></ul><ul><li>Saturated is better. 10ppm at 25 °F </li></ul><ul><li>More air can be trapped in cold water than hot. </li></ul><ul><li>In ponds, </li></ul><ul><ul><li>O 2 ↑ during the day </li></ul></ul><ul><ul><li>O 2 ↓ during the night and on cloudy days </li></ul></ul><ul><ul><li>O 2 can become stratified. </li></ul></ul>
  9. 9. pH <ul><li>Scale of 1 – 14, 7 is neutral </li></ul><ul><li>Preferred range 6 – 9 </li></ul><ul><li>CO 2 from respiration lowers the pH ( ↑acidity) </li></ul><ul><li>Photosynthesis removes C O 2 from the pond and makes the pH higher (more basic) </li></ul><ul><li>Ammonia is more toxic at high pH levels </li></ul><ul><li>Pond water is more acidic in the morning and basic in the afternoon </li></ul>
  10. 10. Alkalinity/Hardness <ul><li>Buffering capacity: ability to resist changes in pH </li></ul><ul><li>Comes from dissolved limestone </li></ul><ul><li>20 ppm CaCO 3 acceptable, 100 ppm or more is ideal. </li></ul><ul><li>Add lime to adjust </li></ul>
  11. 11. Ammonia <ul><li>Excess nitrogen from fish metabolism & waste </li></ul><ul><li>Consumed by algae (ponds) and bacteria (tanks) </li></ul><ul><li>Toxic to fish especially at high pH level </li></ul><ul><li>Closely monitor pH. </li></ul><ul><ul><li>More Adjustable </li></ul></ul><ul><li>If level gets too high, ↓ density of fish and feeding levels </li></ul><ul><li>Level should be less than 2mg/L (ppm) </li></ul>
  12. 12. Salinity <ul><li>Salinity – measure of salt in water in ppt (multiply by 1000 for ppm) </li></ul><ul><li>Our aquaculture tanks are ~ 1.5 ppt </li></ul><ul><li>Fresh water is less than 0.5 </li></ul><ul><li>Brackish water is 0.5 to 17 (Estuaries) </li></ul><ul><li>Ocean water averages 35 </li></ul>
  13. 13. TDS - Total Dissolved Solids <ul><li>Related to salinity </li></ul><ul><li>Ca, Na, Mg, Cl ions in water necessary for homeostasis </li></ul><ul><li>Desired level: 1500 -1900 ppm </li></ul><ul><ul><li> 3 - 3.8 ms/cm </li></ul></ul><ul><li>Convert by multiplying EC (electric conductivity, mS/cm) by 500 to get ppm </li></ul>
  14. 14. Today <ul><li>Water tests </li></ul><ul><li>Tomorrow – </li></ul><ul><ul><li>Aquaculture quiz </li></ul></ul><ul><ul><li>Start shop safety </li></ul></ul>
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