Beef Cattle Terminology continued

Embryo transfer--Removing fertilized ova (embryos) from one cow (donor dam) and placing these embryos into other cows (host cows), usually accompanied by hormone-induced superovulation of the donor dam. More calves can be obtained from cows of superior breeding value by this technique. Only proven producers should become donor dams.

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 of the individual, and the progeny of the individual.

Estrus (heat)--The recurrent, restricted period of sexual receptivity in cows and heifers. Nonpregnant cows and heifers usually come into heat 18 to 21 days following their previous estrus.

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 (straightbred) females of another breed.

Feed conversion (feed efficiency)--Units of feed consumed per unit of weight gained. Also the production (meat, milk) per unit of feed consumed.

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 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.

Gene -- A gene is a discrete segment of the DNA molecule, located at a specific site on a specific chromosome pair. The unique nucleotide sequence of each gene determines its specific biological function. Many genes specify the amino acid sequence of a protein product. Others produce molecules that are involved in controlling developmental and metabolic events. The basic units of heredity that occur in pairs and have their effect in pairs in the individual, but which are transmitted singly (one or the other gene at random of each pair) from each parent to offspring. See also allele.

Gene pool -- A population’s gene pool is composed of all alleles at all gene loci on all chromosomes of individuals within that population. Its content is dependent upon the population’s ancestry, historical isolation, history of natural and artificial selection and cumulative mutation.

Genetic Correlation -- The genetic correlation between two traits is a numerical measure of the extent to which variation in both of them is caused by genes at the same loci. It ranges from +1 (indicating that the two traits are genetically equivalent) through zero (indicating that the two traits are totally independent) to -1 (indicating that alleles causing the first trait to increase cause the other trait to decrease concomitantly). Correlations between two traits that arise because some of the same genes affect both traits. When two traits (i.e., weaning and yearling weight) are positively and highly correlated to one another successful selection for one trait will result in an increase in the other trait. When two traits are negatively and highly correlated (i.e., birth weight and calving ease) to one another, successful selection for one trait will result in a decrease in the other trait.

Genotype--Actual genetic makeup (constitution) of an individual determined by its genes or germplasm. For example, there are two genotypes for the polled phenotype [PP (homozygous dominant) and Pp (heterozygote)].

Genotype By Environment Interaction -- Genotype by environment interaction exists when the difference in phenotypic merit between genetic groups is dependent upon the environment in which those groups are compared. Variation in the relative performance of different genotypes from one environment to another. For example, the "best" cattle (genotypes) for one environment may not be the "best" for another environment.

Gonad--The organ that produces the reproductive cells, the testicle in the male and the ovaries in the female.

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.

Heritability -- Heritability is a numerical measure of the extent to which variation in a trait is genetically determined. Varying from zero to one, it describes the proportion of an individual’s phenotypic superiority or inferiority for the trait expected to be transmitted to its offspring. The proportion of the differences among cattle, measured or observed, that is transmitted to the offspring. The higher the heritability of a trait, the more accurately does the individual performance predict breeding value and the more rapid should be the response due to selection for that trait.