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 being evaluated should be mated to a random sample of females; however, random mating is seldom practiced by purebred beef cattle producers. A simple example involving 18 individuals (14 parents and 4 nonparents) was developed to help students enrolled in a junior-level animal breeding course comprehend how current genetic evaluation methodology, used on an industrywide basis, accounts for nonrandom mating by purebred beef cattle breeders for a maternally influenced trait such as calf weaning weight. With this example, students are able to visualize, algebraically, how a sire's direct and maternal genetic values for weaning weight are adjusted for merit of mates, permitting sires to be compared regardless of mating criteria used by purebred beef cattle producers.