Using cow carcass weight to select efficient cows

Breeding more efficient cows is important for both increasedprofitability and reducedenvironmental impact.Therefore,there is a need to estimate genetic merit for feed intake of cows. Whiledirect measurement of feed intake is difficult, maintenance requirements which accounts for one third of the energy intake of a cow, can be adequately approximated using body weight.Mature cows are not usually weighed, but abattoirs do collect carcassweights of cull cows. Carcase weight varied between 268kg and 400kg. Heritability estimates ofcarcass weight, conformation and fatclass of mature cows were calculated. Mature cows between1095and 7301days of age were included in the study. A total of 4721 cows with weight phenotypes were included, born between 1997and 2020.A mixed linear animal modelwas fitted considering the cow, parity of the cow’s dam, number of calvings per cow, breed and season of birth as fixed effects and coefficient of heterosis and recombination loss estimated from four breedgroupsascovariate effects. The study cows were traced back up to five generations in the pedigree that include 67641 animals in total. The heritability estimates were generated using ASReml. The estimated heritabilitieswere0.64±0.01, 0.49±0.10 and 0.44±0.01 for carcass weight, carcass fat and conformation, respectively. The moderate to high heritability estimates observed in this study indicates there is cull cow carcassweight geneticvariation to allow for genetic improvement and that when data for direct feed intakeis limited, this trait in the meantime couldbe used asa proxy for cow feed intakeand consequently, predicted methane emissions.