ANSC 301

Principles of Animal Nutrition

List of Definitions

-          Abomasum – the fourth compartment of a ruminant’s stomach, which has functions similar to that of the glandular stomach of non-ruminants

-          Absorption – the movement of nutrients (or other compounds) from the digestive tract (or through other tissues such as the skin) into the blood and/or lymph system

-          Acetic acid (acetate) – one of the volatile fatty acids commonly found in silage, rumen contents, and vinegar as a result of microbial fermentation

-          Additive – an ingredient or combination of ingredients added in small quantities to a basic feed mix for the purpose of fortifying the basic mix with trace nutrients, medicines, or drugs

-          ADF – acid detergent fiber; the fraction of a feedstuff not soluble by acid detergent; roughly comparable to crude fiber plus lignin

-          Ad libitum – unrestricted consumption of feed or water

-          Alimentary – having to do with feed or water

-          Alimentary tract – a term synonymous with the digestive or gastrointestinal tract

-          Amino acids – the simplest organic structure of which proteins are formed; all have the common property of containing a carboxyl group and an amino group on the adjacent carbon atom

-          Amino acids, essential – amino acids that must be present in the diet; they include arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine

-          Amino acids, nonessential – amino acids that are found in common proteins but may be partly or completely synthesized by the animal’s tissues; they include alanine, aspartic acid, citrulline, cysteine, glutamic acid, glycine, hydroxyproline, proline, serine, and tyrosine

-          Amylase – any of several enzymes that can hydrolyze starch to maltose or glucose

-          Antibiotic – a substance produced by one microorganism that has an inhibitory effect on another organism

-          Antioxidant – a substance that inhibits the oxidation of other compounds

-          Antivitamin – a substance that interferes with the synthesis or metabolism of a vitamin

-          Anus – the distal opening of the gastrointestinal tract

-          As fed – as commonly used by the animal

-          Ash – the residue remaining after complete incineration of 500°C to 600˚C of a feed or animal tissue. Only metallic oxides or contaminants such as soil should remain

-          Balanced ration (or diet) – a combination of feeds that provides the essential nutrients in the required proportions

-          Basal metabolic rate – the basal metabolism expressed in kilocalories per unit of body size; the heat production of an animal during physical, digestive, and emotional rest

-          Beriberi – a deficiency (acute) of thiamine, one of the B-complex vitamins

-          Bile – a secretion from the liver containing metabolites such as cholesterol and bile acids, which aid in the digestion of fats

-          Biological value – the efficiency with which a protein furnishes the required amounts of essential amino acids; usually expressed as a percentage

-          Bomb calorimeter – an instrument used for measuring the gross energy (GE) content of any material that will burn

-          Butyric acid (butyrate) – one of the volatile fatty acids commonly found in rumen contents and in poor-quality silages

-          Calorie – the amount of energy required to raise the temperature of water from 14.5°C to 15.5˚C

-          Calorimeter – the equipment used to measure the heat generated in a system

-          Carbohydrate – organic substance containing C, H, and O, with the H and O present in the same proportions as in water. Many different kinds are found in plant tissues; some are vital to animal metabolism

-          Carotene – a yellow organic compound that is the precursor of vitamin A

-          Catalyst – a substance that changes the rate of a chemical but is not itself used up in the reaction The use of platinum in hydrogenating unsaturated fats is an example

-          Cecum (caecum) – a blind pouch located at the junction of the small intestine with the colon (the appendix in humans); it is part of the large intestine

-          Cellulose – a polymer of glucose molecules that is resistant to hydrolysis by most digestive enzymes (except some produced by microorganisms)

-          Cholesterol – the most common member of the sterol group found in blood and many other animal tissues; not present in any plant tissues

-          Cholic acid – a family of steroids comprising the bile acids; they are derived from metabolism of cholesterol by the liver

-          Chyme – a semiliquid material produced by the action of gastric juice on ingested food

-          Chymotrypsin – a proteolytic digestive enzyme secreted by the pancreas

-          Coenzyme – an organic molecule required by some enzymes to produce enzymatic activity; vitamin coenzymes include niacin, pyridoxine, thiamine, riboflavin, pantothenic acid, and folic acid

-          Colon – part of the large intestine; divided into the transverse, descending, and ascending segments

-          Complete feed – a single mixture used as the only source of food for an animal

-          Concentrate – any feed containing relatively low levels of fiber (20% or less) and with 60% or more total digestible nutrients (TDN). Opposite of roughage; or a concentrated source of one or more nutrients used to supplement a feed mix

-          Crude fat – the portion of feed (or other material) that is soluble in ether; also referred to as ether extracts

-          Crude fiber – the fibrous, less digestible portion of a feed

-          Crude protein – total ammoniacal nitrogen x 6.25, based on the fact that feed protein, on the average, contains 16% nitrogen; many nonprotein nitrogen compounds may be included

-          Cud – the solid mass of ingesta regurgitated and remasticated in the process of rumination (synonymous with bolus)

-          Deamination – removal of the amino group from an amino acid

-          Defluorination – having the fluorine content reduced to a level that is nontoxic under normal feed use

-          Degradation – conversion of a chemical compound to one that is less complex

-          Dextrin – an intermediate polysaccharide product obtained during starch hydrolysis

-          Diet – a regulated selection or mixture of feedstuffs provided on a continuous or prescribed schedule

-          Digestibility, apparent – the percentage of a feed or nutrient that is apparently absorbed from the gastrointestinal tract as indicated by intake minus fecal output; it differs from true digestibility in that feces contain substances derived from the body, many microbial products, and various secretions, as well as undigested food

-          Digestibility, true – the percentage of a feed nutrient actually absorbed from the gastrointestinal tract

-          Digestion – the process involved in preparing food for absorption

-          Disaccharide – any of several dimers (contains two simple sugars); for example, sucrose (common table sugar) yields glucose and fructose

-          Dispensable amino acid – synonymous with nonessential amino acid

-          Dry matter – the portion of a feed or tissue remaining after water is removed by drying in an oven

-          Duodenum – the first segment of the small intestine

-          Emulsifier – a material capable of causing fat or oils to remain in liquid suspension

-          Emulsify – to disperse small drops of liquid into another liquid

-          Enzyme – a protein formed in plant or animal cells that acts as an organic catalyst

-          Ergosterol – a sterol found chiefly in plant tissues; on exposure to ultraviolet irradiation, it becomes vitamin D

-          Eructation – belching of gas by ruminants as a normal means of expelling gases of fermentation

-          Esophagus – the passageway (tube) from the mouth to the stomach

-          Excreta – the products of excretion, primarily feces and urine

-          Fat soluble – soluble in fats and fat solvents but generally not soluble in water

-          Feed – any material used as food by an animal; same as feedstuff

-          Fermentation – chemical changes brought about by various microorganisms

-          Fibrous – high in content of cellulous and/or lignin (or in cell walls of NDF; neutral detergent fiber)

-          Fistula – an abnormal passage from some part of the body to another part or the exterior, sometimes surgically inserted

-          Forage – crops used as pasture, hay, haylage, silage, or green chop for feeding animals

-          Fructose – a six-carbon monosaccharide; one of the components of sucrose

-          Galactose – a six-carbon monosaccharide; one of the components of lactose

-          Gallbladder – a membranous sac attached to the liver of farm livestock (except the horse) in which bile is stored

-          Gastric juice – a clear liquid secreted by the wall of the stomach; it contains HCl and the enzymes rennin, pepsin, and gastric lipase

-          Gastrointestinal – pertaining to the stomach and intestine

-          Glucose – a six-carbon monosaccharide found in the blood and as a component of sucrose and maltose and other sugars

-          Glycerol – an alcohol containing three carbons and three hydroxyl groups; a component of fat

-          Glycogen – a polysaccharide found in the liver and muscles as a reserve form of quickly available energy

-          Goiter – an enlargement of the thyroid gland sometimes caused by an iodine deficiency

-          Gross energy – the total heat of combustible material burned in a bomb calorimeter

-          Heat increment – the heat that is unavoidably produced by an animal incidental with nutrient digestion and utilization

-          Hydrogenation – the chemical addition of hydrogen to any unsaturated compound (double bond), often to fatty acids

-          Hydrolysis – the chemical process whereby a compound is split into simpler units with the uptake of water

-          Hypervitaminosis – an abnormal condition resulting from the intake of (or treatment with) an excess of one or more vitamins

-          Ileum – the third section of the small intestine

-          Ingest – to take into the mouth

-          Insulin – a hormone secreted by the pancreas into the blood; it is involved in regulation and utilization of blood glucose

-          Intestinal tract – the small and large intestines

-          Jejunum – the middle portion of the small intestine

-          Kcal – an abbreviation for kilocalorie; 1,000 calories

-          Ketone – a group of chemicals that includes acetone, acetoacetate acid, and betahydroxy butyric acid; they are produced in excess when carbohydrate metabolism is low and fat is being metabolized for energy

-          Lactase – an enzyme present in the intestinal juice that acts on lactose to produce glucose and galactose

-          Lactic acid – an organic acid commonly found in sour milk and silage; it is important in the body during anaerobic glycolysis

-          Lignin – a biologically unavailable polymer that is a major structural component of the cell wall of plants

-          Linoleic acid – an 18-carbon unsaturated fatty acid; one of the essential fatty acids; it occurs widely in plant glycerides

-          Lipase – a fat-splitting enzyme; different lipases are produced by the stomach and pancreas

-          Lipids – substances that are diverse in chemical nature but are soluble in fat solvents

-          Lymph – the slightly yellow transparent fluid occupying the lymphatic channels of the body

-          Macrominerals – the major minerals (in terms of the amounts required in the diet or found in body tissues): calcium (Ca), chlorine (Cl), magnesium (Mg), phosphorous (P), potassium (K), sodium (Na), and sulfur (S).

-          Malnutrition – an overall term for poor nourishment

-          Maltase – an enzyme that splits maltose to produce two molecules of glucose

-          Megacalorie (Mcal) – 1,000 kcal or 1 million calories; synonymous with therm

-          Metabolic size – the body weight raised to the ¾ power (W0.75); a means of relating body weight to heat production of an animal

-          Metabolism – the sum of all the physical and chemical processes taking place in a living organism

-          Metabolite – any compound produced during metabolism

-          Metabolizable energy (ME) – digestible energy minus the energy of the urine and combustible gases from the gastrointestinal tract (primarily methane)

-          Methane – a major product of anaerobic fermentation of carbohydrates; found in the rumen

-          Microminerals – the trace elements required by animal tissues that must be in the diet: cobalt (Co), copper (Cu), chromium (Cr), fluorine (F), iodine (I), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silicon (Si), vanadium (V), and zinc (Zn). Synonymous with trace minerals.

-          Minerals – as applied to animal nutrition, elements that are essential to the plant or animal and that are found in its tissues

-          Miscible – capable of being mixed easily with another substance

-          Monogastric – the simple stomach; often applied to nonruminant animals, but technically a misnomer because ruminants have only one stomach with four compartments

-          Monosaccharide – any one of several simple sugars

-          Mucosa – the membranes that line the passages and cavities of the body

-          Mucus – a slimy liquid secreted by the mucous glands and membranes

-          NDF – neutral detergent fiber; the fraction containing mostly cell wall constituents of low biological value

-          Net energy (NE) – metabolizable energy minus the heat increment

-          NFE – nitrogen free extract; consists primarily of readily available carbohydrates such as sugars and starches; part of proximate analysis

-          Nonprotein nitrogen (NPN) – any one of a group of nitrogen-containing compounds that are not true proteins that can be precipitated from a solution; ammonia and urea are examples

-          Nutrient – any chemical substance that provides nourishment to the body

-          Oil – usually a mixture of pure fats that is liquid at room temperature

-          Oleic acid -  an 18-carbon fatty acid that contains one double bond; it is found in animal and vegetable fat

-          Omasum – the third compartment of the ruminant stomach

-          Oxidation – the union of a substance with oxygen; the increase of positive charges on an atom or loss of negative charges

-          Palmitic acid – a saturated fatty acid with 16 carbon atoms

-          Pancreas – an organ located near the stomach; it produces pancreatic juice, which is secreted into the small intestine via the pancreatic duct. It is also an endocrine gland that secretes insulin and glucagon, hormones that control metabolism of glucose

-          Pentosan – a polysaccharide made up primarily of five-carbon sugars; araban and xylan are examples

-          Pentose – a five-carbon sugar such as arabinose, xylose, or ribose

-          Pepsin – a proteolytic enzyme produced by the stomach

-          Propionic acid (propionate) – one of the volatile fatty acids commonly found in rumen contents

-          Protein – any of many complex organic compounds formed from various combinations of amino acids and, sometimes, other nonprotein components

-          Proximate analysis – a combination of analytical procedures used to describe feeds, excreta, and other agricultural products

-          Ration – a fixed portion of feed, usually expressed as the amount of a diet allowed daily

-          Rennin – a milk curdling enzyme present in the gastric juice of young mammals

-          Reticular groove – a muscular structure at the lower end of the esophagus that, when closed, forms a tube allowing milk to go directly into the abomasum; sometimes referred to as the esophageal groove

-          Reticulum – the first compartment of the ruminant stomach

-          Rumen – the second compartment of the ruminant stomach

-          Ruminant – any of a group of hooved mammals that has a four-compartmented stomach and that chew a cud while ruminating

-          Rumination – the process of regurgitating previously eaten feed, reswallowing the liquids, and rechewing the solids (cud)

-          Satiety – the condition of being fully satisfied with food; the opposite of hunger

-          Saturated fat – a fat that contains no fatty acids with double bonds

-          Starch – a polysaccharide that yields glucose on hydrolysis; found in high concentrations in most seed grains

-          Stearic acid – an 18-carbon saturated fatty acid

-          Sterol – an alcohol of high molecular weight, such as cholesterol; a basic compound used to synthesize many vital chemicals for both plants and animals

-          Stomach – the part of the digestive tract in which chemical digestion is initiated in most animal species. It normally lies between the esophagus and the small intestine

-          Sucrose – a disaccharide (common table sugar) composed of one molecule each of glucose and fructose

-          TDN (Total Digestible Nutrients) – a value that indicates the relative energy value for a feed for an animal

-          Thyroxine – an iodine-containing hormone that is produced by the thyroid gland

-          Triglycerides (fat) – an ester composed of glycerol and three fatty acids

-          True protein – a precipitable protein rather than any of several nonprotein compounds

-          Trypsin – a proteolytic digestive enzyme produced by the pancreas

-          Unsaturated fat – a fat containing from one to three fatty acids that contain one or more double bonds

-          Urea – the chief end product of protein metabolism in mammals; one of the main nitrogenous constituents in urine; a synthetic product sometimes used as a nitrogen source in rations for ruminants

-          Urease – an enzyme that acts on urea to produce carbon dioxide and ammonia; it is present in numerous microorganisms in the rumen

-          Uremia – a toxic accumulation of urinary constituents in the blood due to faulty kidney excretion

-          Uric acid – a nitrogenous end product of purine metabolism; it is the principal nitrogen-containing component in urine of birds

-          VFA – volatile fatty acids; acetic acid, butyric acid, and propionic acid

-          Villi – small threadlike projections attached to the interior of the wall of the small intestine to increase its absorptive surface area (singular: villus)

-          Viscera – the organs of the great cavities of the body, which are removed at slaughter

-          Vitamin – one of a group of organic substances that is essential in small amounts for the lives of animals

-          Vitamins, fat soluble – vitamins soluble in fats. This group includes vitamins A, D2, D3, E (tocopherol), and K

-          Vitamins, water soluble – vitamins soluble in water. This group includes ascorbic acid (vitamin C) and the B complex: biotin, choline, cobalamin or cyanocobalamin, folacin, niacin, pantothenic acid, pyridoxine, riboflavin, and thiamine