Consideration of recording plasma Anti-Mullerian Hormone as a correlated trait to reproductive rate in beef cattle to inform selection

Improving productivity is a priority for the Australian beef cattle industry. In part, selection for improved reproductive rate will help achieve this target. One option to inform genetic evaluation of reproduction, increase accuracy of estimated breeding values for reproduction traits and increase rate of genetic gain achieved is to record correlated traits. The potential value of using anti-mullerian hormone (AMH) as a correlated trait for reproductive rate was modelled. Response in genetic gain was considered for two breeding objectives representative of production systems in southern Australia (maternal pasture fed and maternal feedlot) at moderate (h2 = 0.25) and high (h2 = 0.50) assumed heritability and two assumed genetic correlations with cow weaning rate, moderate (rg = 0.30) and high (rg = 0.60). Predicted genetic gain from use of AMH varied considerably depending on the assumed genetic correlation between AMH and weaning rate and ranged from 2% to 20% increase depending on scenario. At the levels of heritability considered for AMH, heritability was less important than the assumed genetic correlation to cow weaning rate. The results indicate that field trials to generate initial genetic parameter estimates of AMH with cow weaning rate are justified.