Simple example illustrating adjustment for merit of mates in a national cattle evaluation program

One of the requirements for an effective progeny test is that each sire bei ng evaluated should be mated to a random sample of females; however, random mating is seldom practiced by purebred beef cattle producers. A simple exa mple involving 18 individuals (14 parents and 4 nonparents) was developed t o help students enrolled in a junior-level animal breeding course comprehen d how current genetic evaluation methodology, used on an industry-wide basi s, accounts for nonrandom mating by purebred beef cattle breeders for a mat ernally influenced trait such as calf weaning weight. With this example, st udents are able to visualize, algebraically, how a sire's direct and matern al genetic values for weaning weight are adjusted for merit of mates, permi tting sires to be compared regardless of mating criteria used by purebred b eef cattle producers.