Animal Nutrition

the fundamental chemical constituents of food

the sum of the processes concerned with the utilization of feed nutrients by animals

economics: feed often represents >50% of production costs on a livestock operation prices have been very volatile in recent years nutrition can impact product quality (marbling- intramuscular fat in beed, omega 3 fatty acids in eggs) environment: greater production per animal has reduced the environmental footprint of animal agriculture

first importance= maintenance (support of body proccesses)–> growth (increase in weight or size) –> reproduction (proliferation of species) –> animal products (used for human consumption) =last importance, high nutrient levels

any substance found in food used for body function 6 classes of nutrients 5 classes of animal feed

water, carbohydrates, proteins, fats, minerals, and vitamins

most important nutrient for animals need 3-4 times as much as solids functions: nutrient transport, body temperature regulation, maintaining body fluids, lubrication deficiencies can affect feed intake water quality can affect intake: salt, sulfates, nitrates acquired by: drinking, part of solid food, body metabolism losses by: urine, feces, sweat and lungs

primary role is to supply energy major component of diet (%) grasses, hay, grains soluble(simple, alpha linkages–easier for body to break down) v. insoluble (complex, beta linkage)

simple, alpha linkages monosaccharides= glucose disaccharides= lactose polysaccharides= starch

complex, beta linkages cellulose hemicellulose lignin -very hard to digest, structural components of plants-stems

building blocks of body composed of amino acids -essential: not formed in body in adequate amount, must be supplied in diet -nonessential: formed in body, do not have to be in diet shortage of any amino acid is limiting proteins are 16% nitrogen, 1 in every 6.25 parts is N analyze for N and multiply by 6.25 to arrive at protein value ruminants can use non-protein nitrogen (NPN) if no more than 50% in diet (urea-elk, cows, etc)

primary role is to supply energy fat is 2.25 times as high in energy as CHO and protein animals are limited in ability to use fat other functions: insulation animal product quality (marbling)

gross energy (GE) \/—————————->fecal energy (FE) \/ digestible energy (DE) \/—————————-> urinary energy (UE). gaseous energy (GE) \/ metabolizable energy (ME) \/—————————->heat increment (HI) \/ net energy (NE) –maintenance and production

gross energy (GE) -heat of combustion -intake energy digestible energy or total digestible energy (TDN) TDN= gross energy-fecal energy metabolizable energy (ME) ME= TDN- (urine and gas) or ME= gross energy- (feces, urine, gas) net energy (NE) NE= gross energy - all losses (maintenance, consumption, movement, and digestion Nem (Net energy for maintenance) = metabolism, activity, heat, cool Nep (Net energy for production) = growth, milk production, fattening, eggs, wool, work Nei (net energy for lactation) Neg (net energy for growth)

structure and balance macrominerals -need in large amounts (Ca, P, Na, Cl, S, Mg) microminerals -need in small amounts, trace minerals -I, Zn, Mn, Co, Cu, Fe, Mo, Se, F excess minerals are toxic

catalysts and regulators fat soluble - A, D, E, K -K is synthesized in rumen -D is synthesized by sunlight on skin water soluble -B complex and C synthesized in rumen

concentrate -grains roughage/forage -grasses and hays protein supplement non-nutritive additives vitamins/minerals

high digestibility (80-90%) high available energy low fiber <18% examples corn, sorghum, barely, molasses, bakery by-products

less digestible (50-65%) high fiber, cellulose low available energy –> but can be utilized by ruminants examples hay, silage, grass, straw why feed roughages? rumen function

feeds containing greater than 20% crude protein contribute amino acids (nitrogen) examples soybean meal, meat and bone meal, urea, and fish meal

works to increase gain efficiency examples antibiotics (minimize disease), ionophores (change rumen function–makes more efficient, makes safer to feed heavier grain diets), flavor compounds, hormone-like compounds (keep feedlot heifers out of heat (MGA))

needed in very small amounts -water soluble and fat soluble -macro and micro (trace) minerals

an approximation of the different nutrients in a sample -dry sample down (moisture versus dry matter) -dry matter (organic matter v ash (inorganic matter-mineral)) -organic matter (protein v non-nitrogenous matter) -non nitrogenous matter (fat v carbs) -carbs (crude fiber v nitrogen free extract)

system for describing chemical makeup of the fibrous components of feedstuffs -defines properties of the plant cell walls a. Neutral Detergent Fiber (NDF): isolates the cellulose, hemicellulose, and lignin (basically indigestible) -negatively correlated to feed intake b. Acid Detergent Fiber (ADF): isolates the cellulose and lignin components of the roughage -negatively correlated to digestibility of the feed