Genetic parameters for calving and conformation traits in Charolais x Montbeliard and Charolais x Holstein crossbred calves

Charolais sires can be mated to Montbeliard or Holstein dairy cows to produce crossbred calves sold for meat production. Heritabilities and correlations between traits can differ when they are calculated within Charolais x Montbeliard or within Charolais x Holstein population. Moreover, the genetic correlation between the same trait measured on Charolais x Montbeliard and on Charolais x Holstein crossbred calves is not necessarily unity. The first objective of this study was to estimate heritability and genetic correlation between traits within Charolais x Montbeliard and within Charolais x Holstein population. The second objective was to investigate if those traits are genetically identical between crossbred populations. Traits studied were calving difficulty, birth weight, height, bone thinness, and muscular development. Data included 22,852 Charolais x Montbeliard and 16,012 Charolais x Holstein crossbred calves from 391 Charolais sires. Heritabilities estimated separately within each crossbred population were similar. Stronger genetic correlations were observed in Charolais x Holstein population compared with Charolais x Montbeliard between calving difficulty and height (0.67 vs. 0.54), calving difficulty and bone thinness (0.42 vs. 0.27), birth weight and bone thinness (0.52 vs. 0.20), and birth weight and muscular development (0.41 vs. 0.18). Bivariate analysis considering observations on Charolais x Montbeliard and on Charolais x Holstein as different traits showed that genetic variances and heritabilities were similar for all traits except height. Birth weight and muscular development were genetically identical traits in each crossbred populations, with genetic correlations of 0.96 and 0.99. Genetic correlations were 0.91 for calving difficulty, 0.80 for height, and 0.70 for bone thinness and log-likelihood ratio tests indicated that they were significantly different from 1 (P <= 0.01). Results show evidence for reranking of Charolais sires for calving difficulty, height, and bone thinness depending on whether they are mated to Montbeliard or Holstein cows.