Genetic Parameters and Correlations for Dairy Weaning, 200‐, 400‐, and 600‐ Day Weights in Beef and Beef‐On‐Dairy Progeny Tested Calves

The expansion of the New Zealand dairy industry has increased the number of lower‐value surplus calves. A value‐add mitigation strategy is integrating them into the beef market. This study investigated the genetic association between growth traits recorded in the Beef + Lamb New Zealand's Dairy‐Beef and the Beef Progeny Test to estimate the genetic correlation between dairy weaning, 200‐, 400‐, and 600‐day weights in beef‐on‐dairy and beef cattle. Single‐trait and bivariate animal models were used to estimate (co)variance components for heritabilities, genetic and phenotypic correlations between traits within the beef‐on‐dairy and beef progeny tests. Estimated heritabilities for beef‐on‐dairy cattle were similar to those for beef cattle. Genetic correlations for growth traits within and across tests were moderate to strong (between 0.46 and 0.99). Phenotypic correlations between traits tended to be lower than the genetic correlations within‐test (0.36 to 0.82). The results indicate that data collected in beef system can usefully inform predictions of growth performance in beef‐on‐dairy systems but that it may not always be appropriate to treat similar measures as the same trait in a genetic model. However, the opportunity exists to combine beef and beef‐on‐dairy data to, simplify breeding, reduce costs and improve genetic merit of beef‐on‐dairy calves.