A Utility Function for Ranking Sires That Considers Production, Linear Type Traits, Semen Cost, and Risk

A procedure was developed to rank AI sires on utility. The utility function con-sidered transmitting abilities for produc-tion, udder depth, teat placement; and foot angle, semen cost, timing of costs and revenues, gene flow, and risk. Weights for type traits relative to produc-tion and risk aversion were based on the literature. A three-generation planning horizon was used. Utility was expressed relative to an average first evaluation non-AI sire. Moderate change in the rela-tive weights of production versus the type traits (3:l versus 2:l) had little effect on sire rankings (rank correlations above.97). The effect of changing risk aversion on sire rankings was subtle except when risk aversion was increased to high levels (three times average levels reported in literature). Rank correlation between se-men utility based on 7 units of semen required to produce a heifer at calving age and nine units of semen required to produce a heifer at calving age (and cor-responding expected calving intervals) was.98. However, the correlation be-tween semen utility based on 5 and 9 units was.91. Similar parameters could be used in ranking sires on utility for many producers. The procedure devel-oped ranked sires differently than indices currently available. (Key words: sire selection, risk, semen utility)