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University of Missouri - Cattle glossary
Category: Agriculture and Industry > Cattle
Date & country: 11/09/2007, USA
Words: 64


Accuracy (of selection)
Correlation between an animal's unknown actual breeding value and a calculated estimated breeding value.

Ad lib feeding
No limit placed on amount of feed intake. Self-feeding or allowing cattle to consume feed on a free-choice basis.

Artificial insemination (AI)
The technique of placing semen from the male in the reproductive tract of the female by means other than natural service.

Average daily gain (ADG)
Measurement of daily body weight change in animal on a feed test. Most tests for bulls are 140 or 160 days long.

Backcross
The mating of a two-breed crossbred offspring back to one of its parental breeds. Example: A Hereford-Angus cross cow bred back to an Angus bull.

Calf crop
The number or percentage of calves produced within a herd in a given year relative to the number of cows and heifers exposed to breeding.

Carcass evaluation
Techniques of measuring components of quality and quantity in carcasses.

Carcass quantity
Amount of salable meat (muscle) the carcass will yield. Cutability is an estimate of this. (See cutability.)

Central test
A location where animals are assembled from several herds to evaluate differences in certain performance traits under uniform management conditions.

Chromosome
Chromosomes are long DNA molecules on which genes (the basic genetic codes) are located. Domestic cattle have 30 pairs of chromosomes.

Closed herd
A herd in which no outside breeding stock (cattle) are introduced.

Collateral relatives
Relatives of an individual that are not its ancestors or descendants. Brothers and sisters are an example of collateral relatives.

Congenital
Acquired during prenatal life. Condition exists at or dates from birth. Often used in the context of congenital (birth) defects.

Contemporary group
A group of cattle that are of the same breed and sex and have been raised in the same management group (in the same location on the same feed and pasture). Contemporary groups should include as many cattle as can be accurately compared.

Culling
The process of eliminating less productive or less desirable cattle from a herd.

Dam
The female parent.

Deviation
A difference between an individual record and the average for that trait for that contemporary group. These differences sum to zero when the correct average is used. A ratio deviation is the ratio less the average ratio or 100.

Dominance
Dominant genes affect the phenotype when present in either homozygous or heterozygous condition. A dominant gene need only be obtained from one parent to achieve expression.

Dystocia (calving difficulty)
Abnormal or difficult labor causing difficulty in delivering the fetus and/or placenta.

Economic value
The net return within a herd for making a pound or percentage change in the trait in question.

Effective progeny number (EPN)
An indication of the amount of information available for estimation of expected progeny differences in sire evaluation. It is a function of number of progeny but is adjusted for their distribution among herds and contemporary groups and for the number of contemporaries by other sires. EPN is lesis than the actual number because the distribution of progeny is never ideal.

Estimate
The process of calculating a particular value from data (verb). The value itself obtained from data (noun). The idea is that the true value is being obtained from the calculated value within limits of sampling variation.

Estimated breeding value (EBV)
An estimate of an individual's true breeding value for a trait based on the performance of the individual and close relatives for the trait. EBV is a systematic way of combining available performance information on the individual brothers and sisters and the progeny of the individual.

Expected progeny difference (EPD)
The difference in performance to be expected from future progeny of a sire compared with that expected from future progeny of the average bull in the same test. EPD is an estimate based on progeny testing and is equal to one-half the estimate of breeding value obtainable from the progeny test records.

F1
Offspring resulting from the mating of a purebred (straightbred) bull to purebred females of another breed.

Frame score
A score based on subjective evaluation of height or actual measurement of hip height. This score is related to slaughter weights at which cattle will grade choice or have comparable amounts of fat cover over the loin eye at the 12th to 13th rib.

Freemartin
Female born twin to a bull calf (approximately 9 out of 10 freemartins will not conceive).

Generation interval
Average age of the parents when the offspring destined to replace them are born. A generation represents the average rate of turnover of a herd.

Half-sibs
Individuals having the same sire or dam. Half-brothers and/or half-sisters.

Heat synchronization
Causing a group of cows or heifers to exhibit heat together at one time by artificial manipulation of the estrous cycle.

Heifer
A female of the cattle species less than three years of age that has not borne a calf.

Heredity
The transmission of genetic or physical traits of parents to their offspring.

Heterosis (hybrid vigor)
Amount by which measured traits of the crossbreds exceed the average of the two or more purebreds that are mated to produce the crossbreds.

Heterozygous
Genes of a specific pair (alleles) are different in an individual.

Homozygous
Genes of a specific pair (alleles) are alike in an individual.

Linecross
Offspring produced by crossing two or more inbred lines.

Marbling
The specks of fat (intramuscular fat) distributed in muscular tissue. Marbling is usually evaluated in the ribeye between the 12th and 13th rib.

Metabolic body size
The weight of the animal raised to the 3/4 power (W0.75); a figure indicative of metabolic needs and of the feed required to maintain a certain body weight.

Metabolism
The transformation by which energy is made available for body uses.

National sire evaluation
Programs of sire evaluation conducted by breed associations to compare sires on a progeny test basis. Carefully conducted national reference sire evaluation programs give unbiased estimates of expected progeny differences. Sire evaluations based on field data rely on large numbers of progeny per sire to compensate for possible favoritism or bias for sires within herds.

Nonadditive gene effects
Favorable effects or actions produced by specific gene pairs or combinations. Nonadditive gene action is the primary cause of heterosis. Nonadditive gene action occurs when the heterozygous genotype is not intermediate in phenotypic value to the two homozygous genotypes.

Open
A term commonly used to indicate a nonpregnant female.

Outcrossing
Mating of individuals that are less closely related than the average of the breed. Commercial breeders and some purebred breeders should be outcrossing by periodically adding new sires that are unrelated to their cow herd. This outcrossing should reduce the possibility of loss of vigor due to inbreeding.

Parturition
The act of giving birth; calving.

Phenotypic correlations
Correlations between two traits caused by both genetic and environmental factors influencing both traits.

Polled
Naturally hornless cattle. Having no horns or scurs.

Possible change
The variation (either plus or minus) that is possible for each expected progeny difference (EPD). This measurement of error in prediction or estimation of EPD decreases as the number of offspring per sire increases.

Progeny testing
Evaluating the genotype of an individual by a study of its progeny records.

Puberty
The age at which the reproductive organs become functionally operative and secondary sex characteristics begin to develop.

Purebred
An animal of known ancestry within a recognized breed that is eligible for registry in the official herdbook of that breed.

Random mating
A system of mating where every female (cow and/or heifer) has an equal or random chance of being assigned to any bull used for breeding in a particular breeding season. Random mating is required for accurate progeny tests.

Rate of genetic improvement
Rate of improvement per unit of time (year). The rate of improvement is dependent on: Heritability of traits considered Selection differentials Genetic correlations among traits considered Generation interval in the herd The number of traits for which selections are made.

Reach
See selection differential.

Recessive gene
Recessive genes affect the phenotype only when present in a homozygous condition. Recessive genes must be received from both parents before the phenotype caused by the recessive genes can be observed.

Reference sire
A bull designated to be used as a benchmark in progeny testing other bulls (young sires). Progeny by reference sires in several herds enable comparisons to be made between bulls not producing progeny in the same herd(s).

Rotational crossbreeding
Systems of crossing two or more breeds where the crossbred females are bred to bulls of the breed contributing the least genes to that female's genotype. Rotation systems maintain relatively high levels of heterosis and produce replacement heifers from within the system. Opportunity to select replacement heifers is greater in rotation systems than in other crossbreeding systems.

Scrotal circumference
A measure of testes size obtained by measuring the distance around the testicles in the scrotum with a circular tape. Related to semen-producing capacity and age at puberty of female sibs and progeny.

Scurs
Horny tissue of rudimentary horns that are attached to the skin rather than the bony parts of the head.

Selection
Causing or allowing certain individuals in a population to produce offspring in the next generation.

Selection differential (reach)
The difference between the average for a trait in selected cattle and the average of the group from which they came. The expected response from selection for a trait is equal to selection differential times the heritability of the trait.

Selection index
A formula that combines performance records from several traits or different measurements of the same trait into a single value for each animal. Selection indexes weigh the traits for their relative net economic importance and their heritabilities plus the genetic associations among the traits.

Sibs
Brothers and sisters of an individual.

Sire summary
Published results of national sire evaluation programs.

Trait ratio
An expression of an animal's performance for a particular trait relative to the herd or contemporary group average. It is usually calculated for most traits as: