Natural Foods

Stock Minnows

Prepared Feeds

used to feed the predator species

(are expensive)

can be supplemental or complete diets.

Often include natural products.

one of the most commonly used is the Oregon Moist Pellet

Problem with this diet is a moisture issue, unless stored frozen, it will dry out. This is a wet diet it will sink, dry will float.

semi moist is easier to store but will also sink slowly.

Practical Diet

Semi-purified Diet

Purified Diet

formulated from natural ingredients (cereal grain, oil seed meals, fish meal, meat by-product, vitamin premix)

ex. Oregon Moist Diet

Semi Purified Diet

often used in research. Contains some natural ingredients, but they are in pure form. 

(Protein=cassein; Lipid=corn oil;Carb=corn starch)

Used when looking at gross energy values.

ingredients are precisely known. Includes synthetic amino acids, fatty acids, and simple sugars. 

Used only in research.

Energy and Growth

Metabolism

result of all chemical energy transformations that occur in a living organism.

Energy is the result of what is obtained in the food.

Energy and Growth

Winburg (1956) 

Thermodynamically Balanced Energy Equation

Qr = energy of food consumed

Qf = energy of fecal loss

Qn = energy of non-fecal nitrogenous loss

Qs = energy of standard metabolism

Ql = energy of locomotor (activity) cost

Qsda = energy of apparent specific dynamic action (feeding)

Qg = energy of growth

Qp = energy of gamete synthesis

Energy and Growth

Anabolism

Energy and Growth

Catabolism

Energy and Growth

anabolism and catabolism

Energy and Growth

amount of energy required to keep the organism from gaining or losing weight.

This varies by species,age,environment,diet,reproductive state

Energy and Growth

extras

-Requirements for carnivores is higher than  herbivore

-Increased protein in diet increases the energy demands for digestion and absorption

-Diets with high mineral content increase metabolism due to increased osmoregulation

-Energy demands are higher in flowing water than static

Energy and Growth

Food stuffs that contain energy

Protein = 5.65 kcal/gram

Carbs = 4.15 kcal/gram

Lipids = 9.4 kcal/gram

Energy and Growth

Key Point - Protein

Feed Constituents

Vitamins

-Distinct from other constitutes because they do bear energy, but are required for normal growth and health.

-Considered catalysts - required for metabolism, but are not destroyed in the process

-Cannot be synthesized by the organism

-Can be produced synthetically 

Feed Contituents

Vitamins

-Water Soluble

      B-Complex (B1,B2,B3)

      Vitamin C (absorbic acid)

-Fat Soluble (can underdose and overdose)

      Vitamins A, D, E, K

Feed Contituents

Vitamins

Hypervitaminous

Hypovitaminous

hyper - fed too many fat-soluble vitamins

hypo- fed too few fat soluble vitamins

neither of these can occur with water soluble vitamins

Feed Consituents

Vitamins

Dosages expressed as

IU's - International Units (the Biological Standards for World Health Organization)

USP's - usually equals IU's (US Pharmacopoeia)

ICU's - (International Chick Units) measurement of responses as elicited by chickens

Top 3 Concerns

1) Water Quality

2) Nutrition

3) Disease

Feed Contituents

Vitamins

storage

Most vitamins are labile (easily degraded or changed to a form not useful) Due to heat,moisture,light.

Therefore, with proper food storage this should not occur. Sometimes antioxidants are added, slows oxidation of vitamins and lipids.

Feed Constituents

Vitamins

Feed Producers -

often use vitamin premixes. For channel catfish and salmonids, vitamin formulations are well known.

However, this is not the case for other species.

Feed Constituents 

Vitamins

problems

Deficiency signs of vitamins are often similar to signs that are the result of diseases.

Vitamins can also be the cause of disease problems, not just the disease agent (pathogen).

Feed Contituents

Minerals

Life Processes Required For

-Development of skeletal structures

-Respiration and Digestion

-Osmoregulation

-Neither created nor destroyed as a result of their funtions

Feed Constituents

Minerals

Major required minerals

(make up 80% of animal ash content)

-Calcium

-Phosphorous

-Sulfur

-Sodium

-Chlorine

-Potassium

-Magnesium

Feed Constituents

Minerals

Trace Minerals

(specific requirements vary among species and among the dietary source of the mineral)

- Iron

- Copper

- Zinc

- Manganese

- Iodine

- Cobalt

- Molybdenum

- Celenium

- Fluorine (only if teeth are present)

Feed Constituents 

Minerals

Feed Constituents

Proteins

- Formed from amino acids

- 20 known amino acids

Feed Constiuents

Proteins

All amino acids contain C, H, O, N and a few contain S.

10 amino acids are essential to fish and cannot be synthesized by the animal

- Phenylaline

- Valine

- Threonine

- Tryptophan

- Isoleucine

- Methionine

- Histidine

- Arginine

- Leucine

- Lysine

(PVT. TIM HALL)

Feed Constituents

Proteins

Methonine and Lysine are only found in high quantities in animal protein and are considered limiting. With plant proteins used as a protein source, they come up short.

The other 10 amino acids can be synthesized by fish using the 10 essential amino acids as precursors 

Optimum level of protein in diet depends on the species, age, condition, reproductive state, environment.

Feed Constituents 

Proteins

Sources of Protein

- Soybean meal

- Fish Meals

- Major feed stuffs (corn)

- Bone meal

- Blood meal

- Distillary by-products

- Beer brewery wastes

- Dried poultry litter

- Egg Waste

- Paper Processing Waste

- Coffee Pulp

- Sugar Cane Waste

Feed Consituents

Lipids

Portion of an animal or plant tissue that can be extracted in a non-polar solvent (ether, chloroform, benzene)

Feed Constituents

Lipids include

Triglycerides

Free fatty acids

Phospholipids

Lipoproteins

Glycolipids

Aliphatic Alcohols

Turpenes 

Steroids

Feed Constitutes

Lipids

Consist of Fatty Acids

-All fatty acids contain carbon, hydrogen, and oxygen

Three classes- 

1)Saturated

2)Monosaturated - One double Bond

3) Polyunsaturated (PUFA) - more than 1 double bond

Three Families - 

1) Oleic

2) Linoleic

3) Linolenic

Feed Constituents

Lipids

Feed ingredients have variable lipid content

Not as important as protein in diet; usually 8% lipid

because:

Some fish will not accept foods high in lipids

Feeds will not extrude properly when made

Bags can get oily

Food will become rancid if stored improperly

Certain lipids can produce an off-flavor in fish

Feed Constituents

Carbohydrates

use as immediate energy

-Contain carbon, hydrogen, and oxygen

-Represented by sugars and starches

-Three groups

-Vary in diets. Typically same amount as protein.

Feed Constituent

Carbohydrates

Three Groups

Monosaccharides (simple sugars) - glucose, fructose, galactose

Diasaccharides (Composed sugars) - sucrose, maltose, lactose

Polysaccharides (Complex Sugars) - starches, cellulose

Feed Constituents

Fiber

Binders

Fiber - no nutritional benefit in most cases; channel catfish cannot digest fiber

Binders - Allows pellet to hold together (1-2% of diet)

include: carboxymethylcellulose, algin, agar, guafluor, commercial products

Non - nutritional variables

Flavor

Odor

Texture

Water Stability

Color

Sinking or Floating

Flavor - may be important b/c if fish taste bad other fish may not eat it

Odor- important when training fish to eat formulated diet

Texture- hard or soft (bass and walleye only soft)

Water Stability - will it break up in water?

Color - determined by ingredients

Sinking or Floating - determined by moisture content

Problems

Toxins

Aflatoxins

Toxic Algae

Red Tide

Ciguatera

toxic metabolite from Aspergillium flavor (blue-grn mold). 

Do not feed if food appears moldy

This mold contaminates oil seed meals

Can cause hepatolema in trout

dinoflagellate problem in mariculture that biomagnifies in the food chain and can be passed to humans.

Problem with mariculture of reef species

Problems

Off flavors

Can be a problem in catfish culture, musty musky taste and odor.

Quality Control is required. They check the quality of fish 2 weeks before, 1 week and 1 day b4 harvest. any off flavor and fish are rejected

If affected fish are placed into clean water, the off flavor will disappear in about two weeks.

Problems

Off flavor

compounds involved

geosmin - synthesized by actinomycetes bacteria and blue green algae

MIB (2-methylisoborneal)

Making Prepared Diets

Ingredients

Pelleting

Ingredients - decide what you want and work with ingredients. There are computer programs that will help develop the least cost rations.

Pelleting - determines wet vs. dry diets

Pressure Pelleting - produces sinking (wet) pellets with a specific gravity > 1. Ingredients are put through a cylinder (dye), and forced through. Comes out in spaghetti like strands and are cut to proper size. Some heating but nothing cooked.

Making Prepared Diets

Pelleting

Extrusion

uses a high temp and a higher pressure than used with pressure pelleting. There is a longer residence time in the mill so that some ingredients are partially cooked. When strands leave the dye they are hot and air is trapped in the pellet (dry float)

These pellets hold together better and have better water resistance.

Also this feeding allows better digestion due to partial cooking. Feed is a little more expensive.

Making Prepared Diets

Pelleting

Quality affected by:

Advantage of Floating Pellets:

Quality- Extent of ingredient grinding, Ingredients used, Moisture content, Operator of equipment

Advantages of floating- monitor fish feeding, monitor growth rate, monitor health

Making prepared diets

Pelleting

Disadvantages of sinking pellets

Hard to tell when fish stop feeding

Nutrients leach from pellets

Hard to use in cage culture

Easy to over or under feed

Have to sample fish to check growth when calculating feeding rate. Increases fish handling.

Feeding Strategies

Depends on species cultures and intensity of culture:

Channel catfish take feed immediately after absorbing yolk sac

Striped Bass must be somewhat trained, but is easy

Walleye are difficult and intense training is required

Marine species cannot be trained

Feeding Strategies

Sometimes training involves feeding natural foods with prepared diets and eventually weeding them off the natural food

Advanced fingerlings do not need to be fed as often (1-2 day) as younger fish (5-8 day)

Fish are typically fed at 3-5% of their bodyweight per day. To maintain fish (no growth) feed at less than or equal to 1% day (3% is standard)

Feeding Strategies

Water Quality 

Winter Feeding

Summer Feeding

Water quality must be watched when feeding fish.

Channel Catfish :

>32C dont feed

21-32C 3% bw/day

16-21C 2% bw/day

7-16C 1% bw/day

<7C dont feed

Winter feeding depends on the latitude - dont feed if ice covered, with mild winter feed alternate days or only on warm days at 1% bw/day

Summer- feed every day, at least 6 days a week

Feeding Methods

Broadcast by hand

Automated feeders - blower of auger on a tractor, atv, or boat. Large farms may use aircraft

Demand Feeders - work on similar ponds to supplement regular feeding

Automatic Feeders - blower with a timer. Often used with tanks and raceways. Typically feed often in small amounts. 

Feed Conversion Ratios 

FCR

-Pounds of feed fed : Pounds of fish produced

Dry weight food : wet weight of fish

Lower the ratio, the better the food conversion

Natural prey consumption along with feeding further lowers the ratio

This is a way of evaluating efficiency.