Genetic parameters for conformation traits, stayability and milk yield for Holstein dairy cattle in Mexico

Heritabilities (h(2)) and genetic (r(g)) and phenotypic (r(f)) correlations were estimated for eleven primary conformation traits, first lactation milk yield (PL1) and stayability to 48 mo of age (HP48) in Holstein cattle in Mexico. Classification and milk production data were used to build two databases, one containing conformation traits and HP48 data (n=3,409), and another containing conformation traits and PL1 data (n=7,044). (Co)variance components were estimated with the REML method, using different animal models. Multi-trait indices were applied to estimate predicted responses to selection for HP48, PL1 and final score (PUFIN). The h(2) values for the studied traits were low to moderate (0.001 to 0.34). The r(g) had values ranging from -0.30 to 0.69 with the highest positive values between HP48 and udder depth (0.52), and HP48 and leg set (0.69). All r(f) values estimated in this study were low. The highest response by generation for PL1 was 747 kg (index 1:0:0), that for PUFIN was 0.90 points (index 2:1:1) and that for HP48 was 0.44 % (index 1:0:0). The high genetic correlations observed here between stayability to 48 mo of age and front teat placement, udder depth, final score and leg set, indicate that incorporating some of these traits into first lactation selection indices could help to genetically improve production, conformation and stayability to 48 mo of age in the Holstein dairy cow population of Mexico.