WHY IS
NUTRITION
IMPORTANT?
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?
Optimal
Conditions
Toxic
Optimal
Marginal
Marginal
Deficient
Toxic
Adequate
Marginal
Marginal
Deficient
(growth, reproduction,
immune function…)
Production parameter
NRC requirement
Stressful
Conditions
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)
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
Lysine
~ 20 amino acids and ~ 10 are essential
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
Terrestrial,
warm-blooded herbivore
GI tract/body length ~ 35
Long, complicated GI tract
to extract maximal
nutrients from plants
Stevens and Hume, 1996
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!
Fish Diets
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
-Can excrete N into environment – no need to store as in
terrestrial animals
- Means fish can efficiently use protein for energy
Protein Deamination
NH4+
NH4+
Glucose
Carbon Skeleton
Fat
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
-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
Fish Diets
Dietary vitamins
- 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
Fish Diets
Which diet to choose for your fish
-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?