Reviewed
Beef production terms and phrases you should be familiar with.
- Accuracy (of selection)
Correlation between an animal's unknown actual breeding value and an estimated breeding value for a trait. - Across-breed EPDs
Procedures and adjustment factors that allow direct comparison of EPDs from animals of different breeds. The adjustment factors, which are updated each year, are based upon estimates of current performance differences among breeds and differences among breeds in genetic base for their evaluations. - Additive genetic effects
For a single locus affecting phenotype (performance), the average effect that one allele has on the phenotype. The sum of additive allele effects across all loci is its breeding value. - Adjusted weaning weight (WW)
An unshrunk, off-the-cow weight adjusted to 205 days of age and to mature dam age equivalence. - Adjusted yearling weight (YW)
An unshrunk weight adjusted to either 365, 452 or 550 days of age. - Alleles
Alternate forms of genes. Because genes occur in pairs in body cells, one gene of a pair may have one effect and another gene of that same pair (allele) may have a different effect on the same trait. - Artificial insemination (AI)
The technique of placing semen from the male in the reproductive tract of the female by means other than natural service. - Backcross
The mating of a crossbred animal to another individual that is more similar to one of the animal’s parental breeds. Example: A Hereford-Angus crossbred cow bred back to an Angus bull. - Beef Improvement Federation (BIF)
A federation of organizations, businesses and individuals interested or involved in performance evaluation of beef cattle. It seeks to build confidence of the beef industry in the principles and potentials of performance testing. The purposes of BIF are to achieve utilization of the most efficient and effective performance evaluation methods, uniformity of procedures, development of programs, cooperation among interested entities, and education of its members. - Birth weight (BW)
The weight of a calf taken within 24 hours after birth. Heavy birth weights tend to be correlated with calving problems, along with other factors. - Breeding objective
The goal of a breeder's selection program, for example, to produce high quality, lean meat at the lowest cost. It may also include a listing of economically related traits to be used as selection criteria to achieve the overall goal. Objectives may vary among breeders due to their genetic and physical resources and their markets. - Breeding value
Transmissible genetic merit of an individual, or the value of that individual as a parent. In the United States and Canada, genetic predictions are expressed as progeny differences rather than as breeding values. Because any parent contributes only half the genes in any one offspring, the progeny difference of an individual is half its breeding value. - Calving difficulty (Dystocia)
Abnormal or difficult labor, causing difficulty in delivering the fetus and/or placenta. Difficult births lead to increased calf and cow mortality and to more difficult rebreeding of the cow. - Calving ease/Calving ease score
The opposite of calving difficulty. An easy calving is one that does not require assistance and does not impose undue strain on the calf or dam. Reported as a numerical score quantifying calving ease, ranging from 1 for an easy, unassisted calving through 5 for an abnormal presentation. - Calving season
The 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 management practices. - Carcass evaluation
Techniques of measuring components of quality and quantity in carcasses and using the information for genetic prediction of carcass merit. - Carcass merit
Desirability of a carcass relative to quantity of components (muscle, fat and bone), USDA quality grade, plus potential eating qualities. - Carcass quality grade
An estimate of palatability based primarily on marbling and maturity and generally to a lesser extent on color, texture and firmness of lean. - Carrier
An individual that is heterozygous, having one dominant and one recessive allele at a given locus. For example, an animal with one gene for polledness and one gene for horns will be polled but can produce horned offspring when mated to another animal carrying the gene for horns. - Central test
A comparison conducted at a single location where animals are assembled from several herds to evaluate differences in performance traits under uniform management conditions. - Chromosome
Chromosomes are paired strands of DNA, with accompanying structural proteins, on which genes are located. Domestic cattle have 30 pairs of chromosomes, one chromosome of each pair having been inherited from each parent. One random chromosome of each pair is transmitted to each egg or sperm cell produced by a parent. - Closed herd
A herd in which no outside breeding stock (cattle) are introduced. - Congenital
A condition that was acquired during prenatal life and therefore exists at or dates from birth. The term is often used in the context of defects present at birth. - Contemporary group
A group of cattle that are of the same sex, are similar in age, and have been raised in the same management group (same location on the same feed and pasture, at the same time). Contemporary groups should include as many cattle as can be accurately compared. - Correlation
A numerical measure, ranging between 0 and 1 that indicates the degree to which two variables vary together in the same direction (positive correlation) or opposite direction (negative correlation). - Crossbreeding
The mating of animals of different breeds or subspecies, frequently resulting in heterosis (hybrid vigor) for many economically important traits. - Culling
The process of eliminating less productive or less desirable individuals from a herd. - Cutability
An estimate of the percentage of salable meat (muscle) from a carcass versus percentage of waste fat. Percentage retail yield of carcass weight can be estimated by a USDA prediction equation that includes measured or estimated values for hot carcass weight, ribeye area, fat thickness, and estimated percent of kidney, pelvic, and heart fat. - Direct effect
The effect that an animal's own genetics has on its own phenotype. For example weaning weight has portion of preweaning growth that is due to the calf's genetics but also has a portion due to the genetics of its dam (see Maternal Effect). - DNA (Deoxyribonucleic acid)
The chemical compound that stores within each cell genetic information unique to an individual. A DNA molecule is composed of two strands of nucleotides bound to one another by chemical bonds between each complementary strand. - Dominant
An allele is dominant when its presence prevents a recessive allele from affecting the phenotype of an individual heterozygous at the locus in question. For example, the allele for polledness (P) is dominant to the allele allowing growth of horns (p), so an animal with the genotype Pp will have the polled form of the trait. - Economic value
The net return for a one unit change (pound or percentage, for example) for an economically important trait under selection. - Effective progeny number (EPN)
An indication of the amount of information available for estimation of expected progeny differences (EPDs) in cattle evaluation. It is a function of number of progeny of a parent but is adjusted for their distribution among herds and contemporary groups and for the number of contemporaries by other sires. EPN is less than the actual number of progeny because the distribution of progeny is never ideal. - Embryo Transfer
Removing fertilized ova (embryos) from one cow (the donor), generally in response to hormone-induced superovulation, and placing these embryos into other cows ( the recipients). More calves can be obtained from cows of superior breeding value by this technique. - Environment
All external (non-genetic) conditions that influence the reproduction, production, and carcass merit of cattle. When environmental influences on phenotypic merit are not properly be accounted for in genetic evaluations, they reduce the accuracy of breeding value estimation and of subsequent selection. - 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 itself and sometimes performance of genetically correlated traits. EBV combines available performance information on the individual and sibs and the progeny of the individual and other relatives. Expected progeny differences (one-half EBV) have replaced EBVs in most breed association programs. - Expected Progeny Difference (EPD)
The difference in expected performance of future progeny of an individual, compared with expected performance at some base point for the population (e.g., the average EPD is 0). The base point may either be fixed or floating. A fixed base sets the average EPD to 0 at a specific point in time (e.g., a specific year). A floating base point changes over years as the number of records analyzed increases. Fixed base points are recommended, especially for traits that have intermediate optima. EPDs are estimated from phenotypic merit of an individual and all of its relatives and are estimates of one-half the animal's estimated breeding value. Genomic marker information is also used to compute EPDs in most cattle evaluations. - F1
Offspring resulting from the mating of a purebred (straight-bred) sire of one breed to a purebred dam of a different breed. - Feed conversion (feed efficiency)
Feed conversion is the units of feed consumed per unit of weight gained or milk produced. Feed efficiency is the inverse of feed conversion and is thus the unit of weight gained or milk produced per unit of feed consumed. - Freemartin
Female born twin to a bull calf and is sterile (approximately 9 out of 10 will be sterile). - Generation interval
Average age of parents when the offspring destined to replace them are born. It should be computed separately for male and female parents and then represents the average turnover rate of bulls and cows in the herd. When other factors are held constant, generation interval is inversely related to the rate of response to selection. That is, rapid generation turnover enhances rate of selection response. - Gene
A gene is a discrete segment of the DNA molecule, located at a specific site (its locus) on a specific chromosome pair. Two copies of each gene exist in each nucleated diploid cell in an animal. Only one gene of each pair is randomly transmitted to the offspring through the gamete. The unique nucleotide sequence of each gene determines its specific biological role. Many genes specify the amino acid sequence of a protein product. Others produce gene products that are involved in controlling metabolic and developmental events. - Genetic correlations
Correlations between breeding values for two traits that arise because some of the same genes affect both traits. When two traits (weaning and yearling weight for example) are positively genetically correlated, successful selection for one trait will result in an increase in the other trait as well. When two traits are negatively genetically correlated (birth weight and calving ease, for example), successful selection for one trait will result in a decrease in the other. - Genotype
The two alleles present at a locus in an individual. For a locus with only two alleles, three genotypes are possible. For example, at the polled/horned locus in cattle, two common alleles are P ( the dominant allele preventing growth of horns) and p (the recessive allele allowing horn growth). The three possible genotypes are PP (homozygous dominant), Pp (heterozygous or carrier), and pp (homozygous recessive). - Genotype x environment interaction
When the difference in performance among genetic groups depends upon the environment in which they are compared. For example, the most profitable breed in the Great Plains is probably not the same as the most profitable breed on the Gulf Coast. Also, different breeds and crosses will be optimum for producing beef for different market specifications and requirements. - Half-sibs
Individuals having the same sire but different dams (or the same dam but different sires). Half-brothers, half-sisters, or half brother/sister. - Heat (estrous) synchronization
Through hormonal manipulation, causing a group of cows or heifers to initiate estrous cycles at approximately the same time. - Heritability
The proportion of the differences among cattle, measured or observed, that is transmitted, on average, to their offspring. Heritability of different traits may vary from zero to one. The higher the heritability of a trait, the more accurately individual performance predicts breeding value and response to selection for that trait should be more rapid. - Heritability estimate
An estimate of the proportion of the total phenotypic variation between individuals for a certain trait that is due to transmissible genetic merit. It is the proportion of total variation for a trait caused by differences among individuals in breeding value. - Heterosis (hybrid vigor)
Amount by which the average performance for a trait in crossbred calves exceeds the average performance of the two or more purebreds that were mated in that particular cross. - Heterozygote
A genotype in which the two alleles at a locus are different, e.g. Pp. - Homozygote
A genotype in which the two alleles at a locus are the same, e.g. PP or pp. - Inbreeding
Matings of parents more closely related than average in the population. Inbreeding decreases the proportion of heterozygous gene pairs in the offspring and increases the proportion of homozygous gene pairs. It increases the frequency of expression of genetic defects caused by recessive genes. Inbreeding may increase prepotency for simply inherited and highly heritable traits. - Independent culling levels
Selection based on cattle meeting specific levels of performance for every trait included in a selection program. Equivalently, culling based on the failure of cattle to meet the required standard for any trait in the program. For example, a breeder could cull all heifers with weaning weights below 400 pounds (or those in the bottom 20% on weaning weight) and yearling weights below 650 pounds (or those in the bottom 40%). - Indicator trait
Any trait that is not associated with income or costs in a production system but is (genetically) correlated to an economically relevant trait. - Linebreeding
A form of inbreeding in which an attempt is made to concentrate the inheritance of some favored ancestor in descendants within a herd. The average relationship of the individuals in the herd to this ancestor is increased by linebreeding, but at the cost of an increased level of inbreeding. - Linecross
Offspring produced by crossing two or more inbred lines. - Locus
The specific location of a gene or mutation on a chromosome. - Marbling
The specks of fat (intramuscular fat) distributed in muscular tissue. Marbling is usually evaluated in the ribeye between the 12th and 13th rib. It is a major factor in assigning USDA quality grade of a beef carcass. - Maternal effect
For weaning weight, the dam's maternal ability which influences preweaning growth. - Maternal heterosis
Amount by which the average performance for a trait in the progeny of crossbred cows exceeds the average performance of progeny of purebred cows of the two or more breed ancestors of the crossbred cows. - National Cattle Evaluation (NCE)
Genetic evaluations conducted by breed associations to compute estimated genetic merit of a population of animals. Carefully conducted national cattle evaluation programs give unbiased estimates of expected progeny differences (EPDs). Cattle evaluations are based on field data and use on information from the individual animal, relatives, and progeny. - Nonadditive gene effects
Effects of specific gene pairs or combinations of gene pairs. Nonadditive gene effects occur when the heterozygous genotype is not intermediate in phenotypic value to the two homozygous genotypes. Undesirable homozygous gene combinations lead to inbreeding depression in inbred populations; whereas favorable heterozygous gene combinations lead to heterosis in outbred herds. - Nucleotide
The subunit of DNA composed of a five carbon sugar, one of four nitrogenous bases (adenine, thymine, cytosine, or guanine), and a phosphate group. - Optimum level of performance
The most profitable or favorable ranges in levels of performance for the economically important traits in a given management system and environment. For example, although many cows produce too little milk, in every management system there is a point beyond which higher levels of milk production will reduce fertility and decrease profit. - Outbreeding (outcrossing)
Mating together of animals that are not closely related. Mild outbreeding is illustrated by mating cows to a sire of their own breed but who is not closely related to them. Such outcrossing may widen the genetic base in a herd and reduce inbreeding accumulation. A higher level of outcrossing is illustrated by crossing two Bos taurus breeds. This generally would result in beneficial heterosis for economically important traits. Crossing of a Bos taurus to a Bos indicus breed is outcrossing of an even greater extreme. These two subspecies have been genetically isolated from one another for a very long time, so heterosis is expected to be greater than from a within subspecies cross. The widest possible outcross is between genetically distinct species, cattle and bison for example. Progeny from such crosses, even when viable, frequently are subfertile or infertile. - Ovulation
Release of the female germ cell (egg or ovum) by the ovary. Cows usually ovulate several hours (up to 15 hours) after the end of estrus or standing heat. - Parturition
The act of giving birth; calving. - Pedigree
A tabulation of names of an individual's ancestors, often only those of the three to five closest generations. Pedigree information is used to establish genetic relationships among individuals to use in genetic evaluations. - Phenotype
The visible or measurable expression of a character; weaning weight, postweaning gain, or reproduction for example. For most traits, phenotype is influenced by both genotype and environment. The relative degree to which phenotypic variation among individuals is caused by transmissible genetic effects is the heritability of a trait. - Phenotypic correlations
The net correlation between two traits caused both by genetic factors and environmental factors simultaneously influencing both traits. - Polled
Naturally hornless cattle. Having no horns or scurs. - Possible change
The amount by which an individual's current EPD might reasonably be expected to change (either upwards or downwards) as more information becomes available in subsequent national cattle evaluations. This measurement of error in prediction decreases as the number of offspring per sire increases. - Postpartum interval
The number of days between parturition and the first postpartum estrus. - Progeny testing
Evaluating the genotype or estimating the breeding value of an individual by evaluating the comparative phenotypic merit of its progeny (offspring). - 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. - Qualitative (categorical) traits
Those traits in which there is a sharp distinction between phenotypes, such as black vs. red or polled vs. horned. Only one or a few pairs of genes are involved in the expression of many qualitative traits. - Quantitative traits
Those traits, such as weaning weight, in which there is no sharp distinction in the range of phenotypes, with a gradual variation from one extreme to the other. Usually, many gene pairs are involved as well as environmental influences affect variation for such traits. - Random mating
A system of mating in which 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. - Rate of genetic improvement
The amount of improvement per unit of time (year). The rate of improvement is dependent on: (1) accuracies in ranking animals for their breeding values of traits considered, (2) selection intensity (a function of the proportion selected, e.g., 1 out of 100 is more intense than 1 out of 10), (3) genetic correlations among traits considered, (4) generation interval in the herd, and (5) the number of traits for which selections are made. - Recessive
Recessive alleles are expressed only when homozygous. They must have been inherited from both parents before the phenotype can be expressed. At the locus for growth or absence of horns, for example, homozygous recessive pp genotype individuals are horned whereas PP and Pp genotype individuals are polled. - Rotational crossbreeding
Systems of crossing two or more breeds where the crossbred females are bred to bulls of the breed contributing the lowest proportion of genes to those females. Rotational crossbreeding systems maintain relatively high levels of heterosis and allow for replacement heifers to be produced from within the system. - Scrotal circumference
A measure of testes size obtained by measuring the distance around the pair of 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 or rudimentary horns that are attached to the skin rather than the bony parts of the head. - Seedstock breeders
Producers whose primary goal is to produce breeding stock rather than animals for feeding and slaughter. Progressive seedstock breeders have comprehensive programs designed to produce animals with optimum genetic merit for the combination of traits to increase downstream profit of commercial beef production. - Selection
Choosing some individuals and rejecting others as parents of the next generation of offspring. - Selection differential
The difference between the average for a trait for selected cattle and the average of the group that was available for selection. The expected response to selection for a trait depends on selection intensity and accuracy of EPDs. - 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 assign relative emphasis to different traits according to their relative net economic importance, their heritability, and genetic associations among the traits. - Selection intensity
The selection differential measured in phenotypic standard deviation units of the selected trait. It is inversely proportional to the proportion of available replacements actually selected to be parents of the next generation. For example, with A. I. compared to natural service, only a small proportion of bulls needs to be selected, and the selection intensity, selection differential, and selection response will be high. - Sibs
Brothers and sisters of an individual; full-sibs have the same sire and dam, paternal half-sibs have the same sire but different dams, and maternal half-sibs have the same dam but different sires. - Single nucleotide polymorphism (SNP)
A variation of base-pairs at a specific nucleotide location in DNA for a defined population. - Sire summary
Published genetic predictions (EPDs) of sires for economically important traits from national cattle evaluation programs. - Terminal sire
Sires used in a crossbreeding system in which all progeny, both male and female, are marketed. For example F1 crossbred dams could be bred to terminal sires of a third breed and all calves marketed. Although this system allows maximum heterosis and complementary of breeds, replacement females must come from other herds. - Trait
Something measured or observed on an individual that is inherited. - Variance
Variance is a statistic that numerically describes the differences (variation) among individuals for a trait in a population. Variance is the average squared deviation (difference) from the average. Without variation, no genetic progress would be possible, because genetically superior animals would not be distinguishable from genetically inferior ones. - Whole Herd Reporting (WHR)
An inventory based performance recording system in which the production of all animals in a breeding herd and the performance of all progeny are accounted for annually. In calf-based systems, by contrast, progeny performance data may be recorded selectively but production information will not gathered on females that do not produce live calves. An inventory based Whole Herd Reporting system is necessary to acquire data for genetic evaluation of some reproductive traits.
Adapted from the 9th Edition of the Beef Improvement Federation Guidelines for Uniform Beef Improvement book. For the full glossary of terms, please visit the Beef Improvement Federation Guidelines website.