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Glossary
Important Glossary of Dairy Nutrition
Acid detergent fiber (ADF)
A chemical analysis that determines the amount of residue (primarily cellulose, lignin and variable amounts of silica) remaining after boiling a feed sample in an acid detergent solution. The ADF value is used to predict the energy content (TDN, NE) of forages.
Acid detergent fiber-crude protein (ADF-CP)
A laboratory test used to measure the amount of heat-damaged protein in hay and haylage, reported on a crude protein basis (nitrogen content multiplied by a factor of 6.25 to convert nitrogen content to a crude protein equivalent basis).
Acid detergent fiber-nitrogen (ADF-N)
A laboratory test used to measure the amount of heat-damaged protein in hay and haylage. The nitrogen (as protein) in this form is unavailable to the animal. (Also – Acid detergent insoluble nitrogen (ADIN))
Ad libitum (ad lib)
A diet offered free-choice, allowing animals to eat as much as they desire; typically allows for 10% leftover from a daily allotment.
Antioxidant
A compound added to feeds to prevent the oxidative rancidity of fats.
As fed
An expression of feed nutrient content with moisture included. Nutrient content on an “as fed” basis is always lower than on a “dry matter” basis.
Ash
The inorganic mineral elements of animals and plants, determined in a laboratory by burning off the organic matter at a high temperature and weighing the residue (ash).
Available protein
The portion of the crude protein that can be digested by the animal; it can represent the proportion of total protein after deducting the ADF-N fraction of a feed.
Average daily gain (ADG)
The average daily liveweight increase of a growing animal, usually expressed in kilograms, grams or pounds/day.
Balanced ration
A 24-hour feed allowance that provides an animal with appropriate amounts and proportions of all nutrients required for a given level of performance.
Buffer
A substance used in livestock rations to help resist changes in the acidity of the digestive tract (e.g., sodium bicarbonate, bentonite).
Byproduct
Feed ingredients produced as a result of industrial manufacturing, plant or animal processing (e.g., distillers’ grains, beet pulp, fish meal).
Carbohydrate
Energy-providing substrate, including starches, sugars, cellulose and hemicellulose. All carbohydrates contain carbon, hydrogen and oxygen, and are usually divided into two fractions: structural (fiber from plant cell wall) and non-structural (sugars and starches from plant cell contents).
Cellulose
A fibrous carbohydrate that is the chief part of plant cell walls.
Chelated mineral
A compound formed between an organic molecule and a mineral that increases mineral bioavailability to the animal, which can reduce excretion of excess minerals in manure use of standard chemical analytical procedures to determine the composition of a feed.
Choline
An essential nutrient, not strictly a vitamin by definition, closely associated with fat metabolism and transport, commonly added to swine and poultry rations. Ruminants generally synthesize adequate amounts, but choline may be added to diets of early lactation dairy cows.
Critical control point (CCP)
A point, step, or procedure in a food process at which control can be applied and is essential to prevent or eliminate a food safety hazard or reduce such hazard to an acceptable level.
Crude fiber (CF)
Chemical analysis that involves extraction of a ground feed sample with diethyl ether followed by sequential boiling in dilute acid and dilute base. Residue is then burned in a furnace; CF is calculated as the difference in weight of the sample before and after burning. CF has been replaced by ADF and NDF fiber fractions in ruminant feeds but is still reported for monogastric feeds.
Crude protein
An estimate of the total protein content of a feed determined by analyzing the nitrogen content of the feed and multiplying the result by 6.25. Crude protein includes true protein and other nitrogen-containing substances such as ammonia, amino acids, nitrates.
Digestibility
A measure of the apparent extent that a feed or nutrient is digested, usually expressed as a percentage of the amount consumed.
Digestible energy (DE)
The apparent energy that is available to the animal by digestion, measured as the difference between gross energy content of a feed and the energy contained in the animal’s feces (gross energy minus fecal energy).
Digestible NDF (NDFd)
A measure of how digestible the neutral detergent fiber fraction of forages is in ruminants. NDFd provides a better estimate of feed value than reliance only on measures of lignin and acid detergent fiber.
Digestion
The process of mechanical, chemical and enzymatic breakdown of consumed feeds into smaller components for absorption in the intestine of the animal.
Direct-fed microbial (DFM)
A live microbial feed supplement that beneficially affects the host animal. Claims include reduced early mortality, increased growth rate, improved feed conversion, egg quality and animal health (e.g., prevent disease and/or aid recovery from illness). Lactic acid producing strains (e.g., Lactobacillus and Streptococcus) are common components of bacterial DFMs.
Dry matter
Feed residue left after all moisture has been removed by drying (e.g., 100% dry matter).
Dry-matter basis
Used to compare nutrient composition or animal intake of feeds in a standardized fashion by eliminating differences in moisture content.
Dry-matter intake
Amount of moisture-free feed or diet consumed.
Effective NDF
A measure for ruminant animals of the amount of neutral detergent fiber (NDF) above a minimum feed particle size in their diet.
Emulsifier
A substance added to products to enable fat or oil to remain in liquid suspension; it is commonly added to milk replacers to prevent fat from separating.
Enzyme
A complex protein produced by living cells that speeds up chemical reactions without being changed or destroyed itself. Enzymes are added to animal feeds to supplement low enzyme production or to improve utilization of poorer quality feeds.
Essential amino acid
Amino acids that must be supplied in the diet, as the animal either cannot synthesize them at all or cannot synthesize them in sufficient quantities to meet its requirements.
Essential fatty acid
Fatty acid that cannot be synthesized by an animal from other sources. Linolenic (18:3n3) and linoleic acid (18:2n6) are essential in the diet; these fatty acids are the basis for the omega-3 and omega-6 classes of fatty acids and are building blocks for longer-chain fatty acids. Fatty acid deficiencies are unusual but can affect skin, coat and reproductive performance.
Ether extract
Laboratory test to approximate the total fat content of a feed; includes some waxes, pigments and other lipids to a minor degree.
Fat-soluble vitamins
Includes vitamins A, D, E and K. Fat-soluble vitamins are stored in body fat reserves. Vitamins A, D and E are supplemented in many livestock rations.
Fatty acid
A major component of fat that is used for energy by the animal. Molecules are composed of carbon and hydrogen in chain-like formation.
Feed efficiency
A ratio describing the amount of feed consumed per unit of production (e.g., gain, milk, eggs).
Feed grade
Term to describe the quality of feedstuffs suitable for animal, but not human, consumption.
Forage
Plants or plant parts fed to, or grazed by, domestic animals. Forage may be fresh, dry or ensiled (e.g., pasture, green chop, hay, haylage).
Germ
The seed embryo.
Gluten
Tough nitrogen containing substance remaining after the flour is washed free of starch.
Gross energy (GE)
Laboratory analysis that measures the total combustible energy in a feed. It is determined by the amount of heat produced when a feed sample is completely burnt in a bomb calorimetre.
International unit (IU)
A standard unit of potency of a biological agent (e.g., vitamin, hormone, antibiotic, antitoxin); also called a USP unit in the U.S.
Iodized
Treated with iodine or iodide.
Ionophore
A carboxylic polyether antibiotic that affects ion transport across cell membranes, inhibits the growth of some gram-positive bacteria and promotes animal growth. Depending on the level fed, an ionophore may also act as a coccidiostat.
Lignin
A complex polymer bound to cellulose that strengthens plant cell walls but is indigestible to animals.
Lipids
Substances found in plant and animal tissues that are insoluble in water, but soluble in benzene or ether; includes glycolipids, phosphoglycerides, fats, oils, waxes and steroids.
Lysine
An essential amino acid for protein synthesis. It is the first limiting amino acid in corn-soybean-based swine diets. Can be added in a synthetic form to diets.
Macro-minerals
Minerals required in relatively large amounts by livestock. Includes calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), chlorine (CI), sulfur (S) and sodium (Na).
Medicated feed
Any feed that contains drug ingredients intended for the cure, treatment or prevention of animal disease, enhancement of feed efficiency or promotion of growth.
Metabolizable energy (ME)
A measure of the useful energy in a feed, representing that portion of the feed gross energy not lost in the feces, urine and eructated gas.
Metabolizable protein
In ruminants, this represents the sum of protein and amino acids reaching the small intestine from ruminally undegraded protein and microbial protein supply.
Methionine
A sulfur-containing essential amino acid for protein synthesis; a limiting amino acid in many ruminant diets. Protected-methionine means resistant to rumen digestion.
Micro-ingredient
A vitamin, mineral, antibiotic, drug or other compound normally required in small amounts and added to diets in milligrams or micrograms.
Micromineral
Minor mineral elements required fed in very small amounts in the ration of animals; includes manganese (Mn), copper (Cu), zinc (Zn), selenium (Se), iron (Fe), cobalt (Co), iodine (I) and fluorine (Fl).
Milk replacer
A substitute for fresh whole milk, fortified with vitamins and minerals: used as a nutrient source for young animals.
Mineral supplement
A rich source of one or more mineral elements.
Minerals
Inorganic feed elements essential for life.
Monogastric
Having a single or simple stomach system (e.g., swine).
Mycotoxin
A substance produced on plants by fungi, particularly during weather stress during the growing or harvest seasons, that is toxic to animals (e.g., vomitoxin, zearalenone, aflatoxin and T-2).
National Research Council (NRC)
A scientific body in the U.S. that has regularly published nutrient requirements for animals based on the latest available research.
Near-infrared analysis (NIRA)
A laboratory analysis of feeds that uses a specific wavelength of near infrared light to estimate nutrient content of feeds based on computerized calibrations of nutrient composition of feedstuffs; a lower-cost analysis compared with traditional wet chemistry. It is dependent on correct calibration to specific feeds for accurate analysis.
Net energy (NE)
The amount of feed energy actually available for animal maintenance and production, representing the energy fraction in a feed left after fecal, urinary, gas and heat losses are deducted from the gross energy value of a feed. Net energy can be further partitioned into the net energy necessary for maintenance, growth and lactation.
Neutral detergent fiber (NDF)
The insoluble fraction containing all plant cell wall components left after boiling a feed sample in a neutral detergent solution. NDF is of low digestibility but can be broken down somewhat by the digestive tract microorganisms. NDF value is used to predict ruminant feed intake.
Non-protein nitrogen (NPN)
Nitrogen not derived from true protein, but usable by rumen microbes to build microbial protein, (e.g., urea).
Non-structural carbohydrate (NSC)
Simple carbohydrates, such as starches and sugars, stored inside the cell that serve as a cellular energy source. Non-structural carbohydrates are rapidly and easily digested by the animal.
Phytase
A feed-additive enzyme that is capable of releasing a matrix of minerals (especially phosphorus) from phytic acid, which is a naturally present mineral-rich component of plant cells indigestible to monogastric animals. Used to reduce the amount of supplemental nutrients fed to meet animal requirements.
Polyunsaturated fatty acid
Typical structure of vegetable oils that have double bonds in the molecular structure. These oils are characterized by being liquid at room temperature.
Prebiotic
A non-digestible feed ingredient that beneficially affects the animal by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon.
Premix
A uniform mixture of one or more micro-ingredients and a carrier, used to facilitate uniform dispersion of micronutrients into a larger mixture. A mineral premix contains higher fortification of trace minerals and vitamins than a mineral supplement.
Protected fat
A fat that has been treated or combined with another substance to prevent its breakdown by microorganisms in the rumen.
Protein
Naturally occurring compounds containing nitrogen, carbon, hydrogen and oxygen, and sometimes sulfur or phosphorus. Proteins are made up of complex combinations of amino acids and are essential for animal growth, production and reproduction.
Ration
The 24-hour feed allowance for an individual animal
Rumen-degradable protein
Portion of ingested protein that is susceptible to digestion by rumen microorganisms; used in the synthesis of microbial protein.
Rumen-undegradable protein (RUP)
The portion of ingested protein that resists rumen degradation and is digested directly in the other stomachs or small intestine; generally a more expensive source of protein.
Saturated fat
A completely hydrogenated fat, solid at room temperature (e.g., animal tallow).
Silage additives
Substances added during the ensiling process to enhance the correct and rapid fermentation of the feed.
Silage
Feed preserved by an anaerobic fermentation process (e.g., corn silage, haylage, high moisture corn).
Soluble protein
An older laboratory measurement that represents the portion of crude protein that goes into solution when mixed in a buffered solution. If 30% of the protein goes into solution, by definition, 30% of the crude protein is soluble.
Starch
A carbohydrate that is a polymer of glucose. Mixture of amylose and amylopectin; represents a store of energy for plants.
Supplement
Feed or feed mixtures used to improve the nutritional value of basal feeds. A supplement is rich in one or more of protein, energy, vitamins, minerals or antibiotics, and is combined with other feeds to produce a more complete feed. Often used interchangeably with concentrate.
Total digestible nutrients (TDN)
The energy value of feedstuffs, comparable to digestible energy in accuracy. TDN over-estimates the energy value of roughages in comparison to grains.
Total mixed ration (TMR)
Homogenous mixture of mechanically mixed ration ingredients, including roughages. TMRs are commonly used in large dairy or beef feedlot operations.
Unsaturated fat
Any fat that is not completely hydrogenated. Unsaturated fats are liquid at room temperature (e.g., corn oil, vegetable oil).
Yeast
Single-cell fungi that improves feed digestion by stimulating microbial activity and stabilizing digestive tract pH. Products packaged as “yeast” consist of cells only; “yeast culture” includes live yeast cells plus growth media.