Post on 30-Jun-2019
transcript
• Nutrition provides an animal with all of the
building blocks to grow, reproduce,
fight infection and maintain health
• Nutrition must be supplied Diet Water Air
Why is nutrition important?
Why is nutrition important?
Under optimal conditions, nutrition doesn’t have to be perfect
But in times of stress, nutrient levels are much more critical - Disease - Poor water quality - Physical or environmental stress (e.g., transportation, handling)
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Stressful Conditions
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NRC requirement
Carbohydrates • Various combinations of carbon and water - Plants use for energy storage and structure - Animals use for energy - Includes:
- Fiber components - Structural - Hemicellulose, cellulose, lignin
- Non-fiber components - Sugars – glucose, fructose, sucrose - Starches – amylose, glycogen
http://www.factmonster.com ipka/A0775714.html 9/06
Amino acids / Protein Amino acids are the building blocks of all proteins including - skeletal muscle and other tissues - scales, skin, fur, feathers - hormones and signaling molecules - immune defenses ~ 20 amino acids and ~ 10 are essential
Lysine
Cysteine
http://es.wikipedia.org/ 9/06
Amino acids / Protein Generally the most expensive dietary component Quality is more important than quantity! - must have the right balance of amino acids - high quality fishmeal is the gold standard
Fatty acids / Lipids - Carbon, Hydrogen and Oxygen
-Most concentrated form of energy storage -Generally long-term energy storage
-Major forms – - Triglycerides (3 fatty acids + glycerol) - Phospholipids and other membrane components - Cholesterol - Sterol hormones -Some fatty acids are essential -Some lipids are essential
http://www.raw-milk-facts.com/images/Cholesterol2.gif 3/08
Fatty acids / Lipids
Ruminant fat (beef, lamb, goat) More saturated,
Fewer double bonds
Poultry and pork fat Mix of saturated and unsaturated
Some double bonds
Fish oil Mostly unsaturated Many double bonds
Vitamins • Chemical compounds required in relatively low amounts
– Biochemical Co-enzymes – Molecular Regulators – Hormone - Vitamin D
- Fat soluble – A, D, E & K -Stored with fat, primarily in the liver - Harder to excrete excess - Water soluble – thiamin, niacin, pantothenate, pyridoxine, B12, biotin, riboflavin, folate, choline, ascorbate -excess can be excreted
Carotenoid pigments • 600 + known carotenoids; • ~ 50 vitamin A precursors • Found in plant & animal products,
but only made by plants • Function as pigment (skin, muscle, fat, egg yolk)
• Important for mating success • Important for marketing food
• Function as an antioxidant / immune modulator
www.plantations.cornell.edu/ images/tomato.jpg
Minerals • Functions
– Structure (e.g., Ca, P, Mg, Mn, S) – Acid-base balance & osmoregulation (e.g, Na, Cl, K, S) – Metalloenzymes (e.g, Fe, Zn, Cu, S)
• At least 21 known to be required • Macrominerals - Ca, P, Na, Cl, K, Mg, S • Microminerals - at least 14 • Ultratrace minerals
Digestion and Absorption • Varies between species due to wild type diet
– Carnivore (meat eater- zooplankton to mammals)
– Omnivore (variety of foods, may have seasonal changes)
– Herbivore (plant eater – phytoplankton to aquatic plants)
• Varies between species due to environment – Terrestrial vs. aquatic – Environmental temperature (cold-blood animals)
Digestion and Absorption
Stevens and Hume, 1996
Terrestrial, warm-blooded herbivore
GI tract/body length ~ 35
Long, complicated GI tract
to extract maximal nutrients from plants
Digestion and Absorption Aquatic,
cold-blooded herbivore
Eats algae and phytoplankton
GI tract/body length ~ 4
Medium, simple GI tract to extract nutrients that are easily digestible and allow time to partially digest plant material
Stoneroller
Digestion and Absorption Aquatic,
cold-blooded omnivore
Eats algae, aquatic plants, insects, other animal
material
GI tract/body length ~ 2
Short, simple GI tract to extract nutrients that are
easily digestible
Digestion and Absorption
? Brook Trout
Carnivore - Crustaceans, insects, fish…
GIT/BL = 0.75
Short GI tract for Readily digestible Food items
Digestion and Absorption • Small intestine secretes many enzymes
– Proteases break down proteins – Lipases and bile salts break down lipids – Many enzymes for non-structural carb digestion
Consumed Absorbed* Carbohydrates………Simple Sugars
Fats……………….….Fatty acids, glycerol
Proteins……………..Amino acids
*Absorbed into blood or lymph
Digestion and Absorption • What about fiber???
•No foregut fermentation
•Little or no hindgut fermentation
•Mastication/grinding
–Carp - pharyngeal teeth
–Milkfish, gizzard shad - gizzard
–Grass Carp
Fish Diets • Efficiency of converting food into meat or eggs
FCR (feed conversion ratio; units = g food per g gain
–Cattle = 6-8
–Hogs = 3
–Chickens = 2-3
–Fish = 1-2 These efficiencies are under optimal conditions, and will drop with underfeeding or
overfeeding!
Why are fish so efficient? -Fish have reduced energy requirements - Cold blooded (poikilothermic) - energy not needed to maintain body T - Aquatic - not fighting gravity - able to excrete nitrogen more easily - Generally utilize readily available nutrients - e.g., unlike a cow that needs microbial digestion to use it’s food
Fish Diets
Using protein for energy
Protein Deamination
NH4+
NH4+
Glucose Carbon Skeleton
Fat
-Can excrete N into environment – no need to store as in terrestrial animals - Means fish can efficiently use protein for energy
Fish Diets
Dietary protein - High dietary protein can be utilized
- e.g., Salmon thrive on >90% protein - No toxicity
- Protein sources - Fish meal (gold standard) - Soybean meal (requires methionine suppl.) - Other animal proteins - Common carp needs (NRC, 1993) 30-35% crude protein 1.74% lysine 0.94% met+cys
Fish Diets
Dietary carbohydrates Fish Diets
-Limited ability to utilize fiber - No foregut fermentation - Very little hindgut fermentation
-Need to provide readily digestible carbohydrates
- Carbohydrates also provide “float” to promote optimal feeding management - Carbohydrate sources
Wheat Corn
Dietary vitamins Fish Diets
- Vitamin C for cartilage synthesis, disease resistance - Source matters (stability!)
-Ascorbic acid (short shelf life) -Encapsulated ascorbic acid (somewhat longer) -L-ascorbyl-2-polyphosphate (long shelf life)
-Common carp needs, among others (NRC, 1993) Vit A 4000 IU/kg Vit E 100 IU/kg Vit C 25-50 IU/kg
Which diet to choose for your fish Fish Diets
-Appropriate for it’s feeding strategy
Carnivorous: Trout, Bass, Perch All Starting fish Protein-based diets
Omnivorous: Catfish, Carp, Koi, Tilapia Can utilize some carbohydrates
How should fish be fed?
- One Feeding Station for every 10 acres - Feed all that the fish will consume in 15 min. - Can feed 1 or 2 times per day - Reduce feed intake when water temperature exceeds 85 and do not feed during hot still cloudy days.