Chapter Six

Feed and Nutrition

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Feed and Nutrition

Raw materials for growth, maintenance & repair

Nutrition = food & water requirements & processes to take

in & use food

Digestion = process food is broken down, absorbed,

distributed & made available to cells

In cells, chemical reactions break down compounds into

simple molecules, releasing energy and molecules for

synthesizing new molecules like proteins.

The sum of these intracellular chemical reactions is called

metabolism.

The Nutrients

Water, proteins, fats, carbohydrates, vitamins & minerals.

Carbohydrates, proteins and fats all provide energy in the form of calories.

Organisms require energy to operate. Require essential and nonessential nutrients. Essential nutrients = ones animals can’t produce in

sufficient quantities, must be supplied in diet. Essential for some species and not for others.

vitamin C for guinea pigs, NHP & humans

Some are required in small amounts. vitamins and minerals

Water

Water is the most important nutrient.

An animal can lose reserve carbohydrate and fat and about 50% of body protein and still survive.

Without water most animals can survive only a few days.

Water is the medium in which all metabolic reactions and body processes take place and is a method for distribution of substances throughout.

A loss of approximately 10 to 20% of body water can result in death.

Protein

Complex molecules made up of long chains of

amino acids arranged in a large variety of

sequences

Proteins are the basic building materials with

which tissues are made.

Enzymes, some hormones, and hemoglobin are

made of proteins.

If deficient caloric intake occurs, body protein is

metabolized.

Fats

Structural components of cell membranes

More calories than carbohydrates or proteins.

One function of fat is to supply and store energy.

Provide thermal insulation, cushion and protect organs,

store and transport fat-soluble vitamins and synthesize

hormones

Brown fat is found in some animals, and can be

metabolized to provide heat.

Broken down into units called fatty acids.

Carbohydrates

Sugars are elementary forms of carbohydrates.

Glycogen = complex sugars easily broken down

by enzymes, used as an energy source of body.

Carbohydrate is main energy source in

metabolism.

Excess carbohydrate is stored as glycogen in

liver and muscle tissue.

When storage areas are full, carbohydrate is

converted to fat.

Vitamins

Function to promote chemical

reactions for normal metabolism Non-fatty tissues contain water-

soluble vitamins (vitamins C & B).Water-soluble vitamins supplied daily because they are not

easily stored.

Fat-soluble vitamins A, D, E and K are found in fatty parts of plants and animals.

Digestion and metabolism of fat supply fat-soluble vitamins.Fat-soluble vitamins in excess are stored in fat, not excreted.

Excess or deficiency vitamin = serious diseaseGuinea pigs and NHPs get scurvy, a result of feed stored

too long or at too high a temperature.

Minerals 21 inorganic elements are necessary

to sustain life. Ca, P and Na are used as structural

components & as electrolytes in salt balance. Minerals are required in trace

amounts, & used in a variety of processes. Iron = oxygen carrier in hemoglobin found in RBC.

Mineral deficiency or excess in the diet can cause serious disease.

Ca is necessary for contraction of muscles, including heart muscle.

Deficiency in Ca = poor bones Bone Ca goes to blood to help maintain heart muscle contraction.

Energy Metabolism

Diets are formulated for each species. Energy is needed to maintain life processes.

respiration, cell metabolism, movement, digestion, nerve impulse transmission, cell division & growth

1 calorie is heat necessary to raise temperature of one gram of pure water at 14.5°C to 15.5°C.

Feed bag has a chart that tells how many Kcal of energy contained in the diet. can be used to determine how much to feed

Feeds vary considerably in total caloric content. carbohydrates = 4.1 Kcal/gram, proteins = 5.6

Kcal/gram and fats = 9.4 Kcal/gram

(Images) Dog Eating

Feedstuff Evaluation

Proximate analysis used to formulate diets. Analytical tests provide data on a feed sample. Consuming proper amount of commercial diet &

water = all nutritional requirements. Supplements contribute to daily caloric intake.

May result in consuming less than daily diet and interfere with dietary balance.

Treats may be a necessity, for delivering medication or for psychological enrichment.

Supplementation may be required during rapid growth, pregnancy, lactation or geriatrics.

Available Forms of Feed

Ground feed = powdered dietCommonly used for poultry but OK for other animals.

High dust content may cause respiratory problems in some species

Pelleted feed made by grinding and molding into a variety of shapes & sizes.High fat content feeds

don’t hold together well.

Abundance of powdered feed

in the feed bag = questionable

quality & should be reported.Fed to rabbits, guinea pigs, rodents and farm animals.

Available Forms of Feed II

Extruded = high pressure & heat in tapered mold.

Semi-moist feed is available for dogs and cats. High calories = unsuitable for caged animal use.

May contribute to dental problems.

Canned feed is comparatively expensive.Can be used to tempt sick animals to eat or deliver

medication by hiding it in the food.

Hay given to ruminants, rabbits and guinea pigs.Contaminated hay can affect health.

Hay cubes are a suitable alternative.

Commercial Diets

Standard diets are available with data on protein, fiber, fat or other nutrient content

Certified feed measures pesticides & heavy metal contaminants.

Contaminants usually certified to be below a particular level.

Autoclavable and irradiated feed fed to animals in barrier facilities.Formulated to account for autoclaving which destroys

significant portions of certain nutrients.Diets can also be sterilized with radiation.

Purified diets are made from ingredients such as starch, glucose, sucrose and casein.

Practical Aspects of Feeding

Water must be available at all times.A sipper tube may be plugged preventing animal from

reaching water, so technician quickly learns to identify such problems and correct them before the animals demonstrate ill effects.

Addition of substances to water may cause animals to decrease intake because of taste.

Feeders designed for a type of feed. Feed accessible, clean, uncontaminated.

J-feeders become clogged with fines.

Technicians monitor feed intake &

are aware of any variations.

Diet & Water Problems

Sensitivity to diet changesoften fail to eat or exhibit diarrheamake feed changes gradually

Growth and reproduction two most demanding physiological statesRodents begin eating feed 10-14 days after birth.

Cats and dogs begin to eat at 3-4 weeks old. Extra feed should be provided to the nursing female.

Food and Water Intake Animals overactive and distressed within

24 hours without water. Hair coat appears dull and shaggy. Dry food intake decreases dramatically, as does

the production of urine and feces Dehydration also due to a disease or faulty watering.

Decreased food intake = significant

weight loss, obvious overall debilitation, &

prominent skeletal structure. Decreased food intake can also be result of an experimental

procedure or a disease process

In group-housed animals, a dominant animal may prevent

a subordinate animal from reaching food.

Feed Storage & Room Management

Proper handling vital to health & nutrition.Direct bearing on economics of facility management.

Storage environment cool, dry, well ventilated & no direct sunlight.

Store on platforms or shelves above floor & at least 6 inches from the wall to allow for cleaning & air circulation. If wood is used, seal to allow proper cleaning.

Keep open bags in plastic-lined cans w/ tight-fitting lids.

Shelf Life Milling date = date food was made. Feed loses nutritional value after shelf life expires. Purified diets & some diets containing vitamin C

have a short shelf life (3 months or less).Other types can be stored up to 6 months.Storage under less than optimal conditions (for example,

high heat or humidity) shortens shelf life. On receipt, check milling date, mark w/ “use by”

Check: clean, dry, unstained, not torn or damagedReject any of these defects as possible contamination.

Store special feeds w/ drugs or chemicals away from regular feed storage room.Store detergents & chemicals separately.

Additional Reading

Frandson, R.D. Anatomy and Physiology of Farm

Animals. 5th ed. Lea and Febiger, Philadelphia,

PA. 1992.

Nutrient Requirements of Laboratory Animals. 4th

ed. National Research Council. 1995.

Jurgens, M.H. Animal Feeding and Nutrition.

Kendall/Hunt, Inc., Dubuque, IA. 1988.