FARM ANIMAL NUTRITION

ANIMAL SCIENCE 110

Fall 2001

NUTRIENTS

• A nutrient is any feed constituent that functions in support of life.

• Structural components of cells and organs.• Sources of energy for maintenance &

production.• Regulation of body processes.• Accessory functions such as growth,

reproduction, lactation, etc.

SIX CLASSES OF NUTRIENTS

• WATER

• CARBOHYDRATES

• FATS

• PROTEINS

• MINERALS

• VITAMINS

WATER

• Transport of other nutrients• Temperature regulation• Gives body shape or form• Involved in most biochemical reactions• Clean fresh water is essential for all animals• Embryo is 90% water, newborn is 70% water and

market animal is 50% water• Several factors affect water intake

CARBOHYDRATES

• “CH2O”• Monosaccharides

– Glucose, Fructose & Galactose

• Disaccharides– Sucrose, Maltose & Lactose

• Polysaccharides– Starch, Glycogen, Hemicellulose & Cellulose– Lignin (Indigestible & not a true carbohydrate)

FATS

• Energy – 2.25 times the energy of CH2O

• Most are triglyceride (glycerol + 3 fatty acids)• Saturated – no double bonds – animal origin• Unsaturated & polyunsaturated – plant origin• Precursors of cholesterol, prostaglandin and

structural components of cells• Some vitamins are fat soluble

PROTEINS

• Contain nitrogen – long chain amino acids• Average 16% N (100/16 = 6.25)• Plants synthesize amino acids from

elements in the environment• Animals require a dietary source of amino

acids• Rumen microorganisms can synthesize

amino acids and protein

PROTEINS

• An essential amino acid is one that can not be synthesized at a rate which would provide normal growth

• Nonessential amino acids can be synthesized from other amino acids

• A limiting amino acid is one present in the lowest amount relative to the requirement– Lysine, methionine & tryptophane are likely to be

limiting in diets for monogastric animals

ESSENTIAL AMINO ACIDS

• Phenylalanine• Valine• Threonine

• Methionine• Arginine• Tryptophane

• Histidine• Isoleucine• Leucine• Lysine

NONESSENTIAL AMINO ACIDS

• Alanine• Aspartic Acid• Citrulline• Cystine• Glutamic Acid*

* Required by chick for optimal growth

• Glycine*• Hydroxyproline• Proline*• Serine• Tyrosine

MINERALS

• Inorganic elements• Structure – skeleton & teeth• Acid – base balance in body fluid• Osmotic pressure in cells• Maintain acidity of digestive juices – most

enzymes are pH specific• Muscle contraction & CNS• Interact with vitamins (Se-Vit E)

MINERALS

MACRO• Calcium• Phosphorous• Sodium• Chlorine• Sulphur• Potassium• Magnesium

MICRO• Iron & Copper• Iodine & Fluorine• Cobalt• Manganese• Molybdenum• Selenium• Zinc

VITAMINS

• Organic compounds which function as metabolic regulators

• Fat soluble vitamins– “A” maintenance of epithelial tissue– “D” calcium & phosphorous metabolism– “E” antioxidant – (selenium)– “K” blood clotting

WATER SOLUBLE VITAMINS

• B1- Thiamine

• B2- Riboflavin

• B6- Pyridoxine

• Pantothenic Acid• Folic Acid

• Niacin

• B12- Cyanocobalamin

• Choline• Biotin• C - Ascorbic Acid (not

in livestock)

CONCENTRATES vs ROUGHAGES

• Concentrates include cereal grains, oil meals, molasses and dried milk products

• They are high in energy, low in fiber and highly digestible (80% to 90%)

• Roughages include hay, straw, silages, green chopped forage and pasture

• They are 50% to 60% digestible except for straw which is lower

PROXIMATE ANALYSIS of FEEDS

• Moisture or dry matter – oven

• Crude Protein – Kjeldahl procedure

• Crude Fat – ether extract

• Crude Fiber – acid/base digestion

• Mineral – ash

• Nitrogen Free Extract – determined by difference (primarily starch & sugar)

VAN SOEST & Other Procedures for Fiber Analysis

• Neutral Detergent Fiber (NDF) – plant cell walls [hemicellulose, cellulose & lignin]

• Acid Detergent Fiber (ADF) – cellulose & lignin

• NDF-ADF = hemicellulose• Acid Detergent Lignin (ADL)• Near-infrared Reflectance (NIR) –

spectrometer to predict forage quality

TOTAL DIGESTIBLE NUTRIENTS (TDN)

• Chemical analysis does not indicate availability of nutrients to animal

• Apparent Digestibility– [(Nutrient in Feed – Nutrient in Feces)/

Nutrient in Feed] x 100

• TDN = [Dig.Protein + Dig.Crude Fiber + Dig.NFE + (Dig.EE x 2.25)] x 100

ENERGY DEFINITIONS

• Calorie – Amount of heat energy required to raise 1 gm of water 1oC (14.5o to 15.5oC)

• Kilocalorie – 1000 calories

• Megacalorie – 1000 Kilocalories

NET ENERGY SYSTEM

• Gross Energy (GE) = Total heat of combustion

• Digestible Energy (DE) = GE – Fecal Energy. DE is similar to TDN

• Metabolizable Energy (ME) = DE – Urine & Gas Energy

• Net Energy = ME – Heat Increment• Nem or NEg or NEl