Evaluating Genetic Parameters And Trends Of Weight Traits For The Hays Converter Beef Breed By Multiple-Trait And Random Regression Models

Hays Converter (HC), developed by Harry Hays in the 1950’s, was the first registered Canadian beef breed. A synthetic, it originally combined genetics from Holstein, Hereford and Brown Swiss with later immigration of Angus. It is well adapted to the harsh Canadian climate and progeny of the breed reach market weight early, convert feed to gain efficiently and have excellent carcass quality and yield. The objective of this study was to evaluate the genetic changes in birth, weaning and yearling weights of HC over time by multiple trait (MTM) and random regression (RRM) models. Estimates of variance components, heritability and genetic correlation obtained from both models had similar trends along the growth trajectory, although the values were numerically different. Selection of sires had a direct effect on the genetic trends of weight traits over time. There was a considerable reduction in trends from 2004 to 2008 while they gradually improved again through 2016. Exclusion of data from Angus influenced offspring revealed a reduction in the genetic trends for 100% HC animals during recent years. Compared to MTM, RRM does not pre-adjust records to standard ages and thus avoids editing of data in order to conform to prescribed windows of age. Therefore, it may be suggested as the preferred method, giving a more accurate analysis, especially when a significant amount of data has been collected at non-standard ages.