WHY IS NUTRITION

IMPORTANT?

• 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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Optimal Conditions

Stressful Conditions

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NRC requirement

WHAT NUTRIENTS ARE

ESSENTIAL?

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

HOW DOES AN ANIMAL USE IT’S FOOD?

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?

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.

BETTER FEED = BETTER FISH

QUESTIONS?