Economic weights of current and new breeding objective traits in Aberdeen Angus

Breeding values estimated for growth, calving performance, and exterior traits are currently combined into simple selection indices for bulls, cows, and heifers of the Aberdeen Angus breed. To establish a comprehensive economic index for this breed, the absolute and relative economic weights (EW) for a complex of 16 production, functional, carcass, and feed efficiency traits were calculated. The absolute EW of a trait expressed the difference in the present values of profit that will be obtained from the descendants of a bull with the average breeding value for this trait, and descendants of a bull with the breeding value one unit higher than the average one. The relative EW of a trait was defined as the standardised EW of a trait (i.e. EW per genetic standard deviation) expressed as percentage of the sum of standardised EWs of all evaluated traits. Sensitivity analysis was conducted to explore the EW of traits under variable production and economic conditions. Variability in the marketing strategy, in product prices and costs, and in trait means was considered in this analysis. Relative EW of the feed efficiency of breeding heifers and of cows reached 4%. The highest relative EW was obtained in three growth traits: weight gains of calves from birth to 120, from 120 to 210, and from 210 to 365 days of age (66% combined). The survival rate of calves until weaning and cow productive lifetime reached 11% and 8% of the total economic importance of traits, respectively. These growth and functional traits accounted for 84% (in marketing strategy involving selling breeding animals) to 90% (in populations with high growth intensity) of the total economic weight of all 16 evaluated traits. Therefore, these traits should be considered as new selection criteria when constructing a comprehensive selection index for the Czech Aberdeen Angus population in future.