The fourth digestive chamber of the digestive system of most ruminants. The abomasum is located after the forestomachs (rumen, reticulum and omasum) and before the first segment of the small intestine (i.e., the duodenum); It is sometimes referred to as the "true" stomach because of its acid-secreting ability, which is found in most other mammalian species.

The degree with which a measurement matches the actual, true or target value (see also Precision).

Condition characterized by a low rumen pH (below 6). The normal rumen function are impeded usually because too much concentrates were fed.

A latin word that means "to one's pleasure." In nutrition, ad libitum (abbreviated "ad Lib") refers to feeding management in which animals are fed without restriction. Cows are usually considered fed ad libitum when the refusals (orts) amount to approximately 5 to 10% of what has been offered the day before.

Allometric equations take the general form Y = aM^b, where Y is some biological variable, M is a measure of body size, and b is some scaling exponent. See West et al. (2012) for more details.

The growth of body parts at different rates, resulting in a change of body proportions.

One of the 20 building block units of protein. Amino acids contain both an amino group (NH₂) and an acid or carboxyl group (COOH).

A pungent gas. Ammonia is extensively used to manufacture fertilizers and nitrogen containing compounds. Also, ammonia is the end-product of protein degradation by ruminal bacteria.

The part of the metabolism in which metabolites are used in the growth and repair of body tissues.

A disease due to a deficiency in red blood cells or in hemoglobin that carries oxygen in the blood.

Protein released in the blood that is generated in reaction to a foreign protein (antigen) that has entered the body. Antibodies produce immunity against certain micro-organisms or their toxins.

Desire for food that can be quantify by measuring dry matter intake.

Reproductive procedure by which semen previously collected from sires, packaged in “straws” and frozen in liquid nitrogen is thawed and manually deposited in the uterus of a cow in estrus, in the hope of conception. Artificial insemination is a technology that allows for genetic improvement based on selection and use of superior sires.(see also Timed Artificial Insemination).

A method of expressing the concentration of a nutrient in a feed. For example, a feed containing 12% crude protein on a dry matter basis contains 12 g of protein for each 100 g of feed "as-is" (or "fresh"). When feed ingredients are added to a mixer, they are weighted on an "as-is" of "fresh" basis. See also "Dry Matter Basis.

(see minerals)

Single-cell organisms living either independently or in close association with other living organisms. Often referred to as microbes or microorganisms because of their microscopic size. Some bacteria are beneficial, but others cause infectious diseases.

A small stony concretion that may form in the stomachs of certain animals, especially ruminants. Bezoars are caused by a buildup of material in the gastrointestinal tract that the stomach can't digest.

A liver secretion that is necessary for proper digestion of fats.