TERMS TO KNOW:
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.
ARTIFICIAL INSEMINATION (AI): Te technique of placing se- men from the male in the reproductive tract of the female by means other than natural service.
BALANCE: Te harmonious relationship of all body parts, blended for symmetry and appearance. A steer that is poorly developed in the hindquarter lacks balance.
BIRTH WEIGHT (BW): Te weight of a calf taken within 24 hours aſter birth. Heavy birth weights tend to be correlated with calving problems, but the conformation of the calf and the cow are contrib- uting factors.
BREEDING PROGRAM GOALS: Te objective, or “direction” of breeders’ selection programs. Goals are basic decisions breed- ers must make to give direction to their breeding program. Goals should vary among breeders due to relative genetic merit of their cattle, their resources and their markets.
BULL: An uncastrated male of any age. CALF: A young animal of either sex, under 1 year of age.
CALVING SEASON: Te season(s) of the year when the calves are born. Limiting calving seasons is the first step to performance testing the whole herd, accurate records, and consolidated manage- ment practices.
CASTRATE: To remove the testes. CHARACTERISTIC: A physical or behavioral trait in an animal. CONDITION:Te degree of fatness in animals. CONFORMATION: Te general structure and shape of an animal. CRYPTORCHID: A male bovine with one or both testes undescended.
CULLING: Te process of eliminating less productive or less desir- able cattle from a herd.
ENVIRONMENT: All external or non-genetic conditions that influ- ence the reproduction, production, and carcass merit of cattle.
ESTRUS: Te period when a cow will accept a bull for breeding, heat period. FEED CONVERSION (FEED EFFICIENCY): Units of
GENERATION INTERVAL: Average age of the parents when the off- spring destined to replace them are born. A generation represents the average rate of turnover of a herd.
GENES: Te basic units of heredity that occur in pairs and have their effect in pairs in the individual, but which are transmitted sin- gly (one or the other gene at random of each pair) from each parent to offspring.
GENETIC CORRELATIONS: 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 re- sult in an increase in the other trait. When two traits are negative- ly 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, or constitution, of an individ- ual determined by its genes or germplasm. For example, there are two genotypes for the polled phenotype [PP (homozygous domi- nant) and Pp (heterozygous)].
GENOTYPE-ENVIRONMENT INTERACTION: Variation in the relative performance of different genotypes from one environment to another. For example, the “best” cattle genotypes for one environ- ment may not be the best for another environment.
GET:Calves sired by the same bull.
GONAD: Te organ that produces the reproductive cells, the testi- cle in the male and the ovaries in the female. HERD SIRE: Te principle breeding bull in a herd.
HEREDITY:Te transmission of genetic or physical traits of parents to their offspring.
HERITABILITY: Te proportion of the differences among cattle, measured or observed, that is transmitted to the offspring. Herita- bility varies from zero to one. Te higher the heritability of a trait, the more accurately does the individual performance predict breed- ing value and the more rapid should be the response due to selec- tion for that trait.
HOOKS: Hip bones.
INBREEDING: Production of offspring from parents more closely related than the average of a population. Inbreeding increases the proportion of homozygous gene pairs and decreases the proportion of heterozygous gene pairs. Also, inbreeding increases prepotency and facilitates expression of undesirable recessive genes.
feed con-
sumed per unit of weight gained. Also the production (meat, milk) per unit of feed consumed.
FERTILITY TEST: Analysis of semen for live sperm count, tests a bull’s ability to produce offspring.
FINISH:Te degree of fatness.
FREEMARTIN:Female born twin to a bull calf (approximately 9 out of 10 freemartins will not conceive).
70 | TEXAS LONGHORN JOURNAL | HERD SIRE EDITION
INDEPENDENT CULLING LEVELS: Selection of culling based on cattle meeting specific levels of performance for each trait included in the breeder’s selection program. For example, a breeder could cull all heifers and weaning weights below 400 pounds (or those in the bottom 20 percent on weaning weight) and yearling weights below 650 pounds (or those in the bottom 40 percent).
LINEBREEDING: A form of inbreeding in which an attempt is made to concentrate the inheritance of some one ancestor, or line of ancestors, in a herd. Te average relationship of the individuals in the herd to this ancestor (outstanding individual or individuals) is increased by linebreeding.
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