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 “CH 2 O” 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 CH 2 O 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 B 1 - Thiamine B 2 - Riboflavin B 6 - Pyridoxine Pantothenic Acid Folic Acid Niacin B 12 - 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 1 o C (14.5 o to 15.5 o C) 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 Ne m or NE g or NE l