Multiple Trait Selection Committee

Economically Relevant Traits
     A pair of Colorado State University staffers considers expected progeny difference (EPD) values most useful when the numbers represent sensible traits. According to Bruce Golden and Mark Enns, the typical sire summary offers EPDs for many traits that do not directly affect producer profitability.
     “Economically relevant traits (ERTs) are those directly associated with the revenue stream or cost of production,” Golden says. “They affect future profitability. Indicator traits are those that add accuracy to the prediction of ERTs.”
     While calving ease is an economically relevant trait, Golden calls birth weight, pelvic area and gestation length indicator traits for calving ease. Similarly, calving interval, milk production and fleshing ability would be included among indicators of mature cow fertility. While measurement of indicator traits is necessary, Golden and Enns suggest that EPDs be calculated only for economically relevant traits.
     Their suggested list of ERTs includes weaning weight direct, weaning weight milk, yearling weight, carcass weight, mature weight, cow maintenance feed requirement, docility, stayability, probability of heifer pregnancy, probability of calving ease, calving ease maternal, days to 1,200 pounds (finish), days to 0.4 inch backfat, and days to quality grade.
     According to Enns, a focus on economically relevant traits would remove extraneous information and make it easier for producers to evaluate their genetic selection decisions.
     “With ERTs, we can develop an individualized selection index for a producer and increase the probability of making profitable decisions,” Enns states.

Genetic Evaluation Down Under
     Rather than expected progeny difference values, Australia’s genetic evaluation system calculates expected breeding values (EBVs) as a tool for genetic selection. However, researchers at the University of New England, in New South Wales, have developed a system for combining the EBVs of 19 standard traits into a single selection index for profit.
     According to David Johnson, of the Animal Genetics and Breeding Unit, BreedObject is the name of the software developed as a decision aid for seedstock breeders and commercial bull buyers. Specific to a producer’s own breeding goal and market objective, a selection index may be individually customized. Utilizing EBVs for various traits, BreedObject will assign, to bull candidates under consideration, a single index value representing potential profit per cow in that particular herd.
     Johnson also said research is under way to develop EBVs for feed efficiency and traits such as structural soundness and temperament. Also coming is a system for making comparisons across breeds and with hybrids.

—Troy Smith