Breeding and Genetics: Applications and Methods in Animal Breeding—Dairy II

The objective of the present study was to estimate genetic correlations between feed intake and type traits with a view to considering the potential of indirect genetic selection for feed intake using type traits in dairy cattle. Feed intake data on 119,388 first lactation Holstein cows were obtained from Dairy Production Centre of Expertise, Valacta. Type trait records on 93,619 cows were obtained from Holstein Canada and were recorded during 1 to 365 d of first lactation. Feed traits included 305-d dry matter intake (DMI), 305-d net energy of lactation intake (NELI) and 305-d crude protein intake (CPI). Type traits included dairy strength, angularity, body depth, stature and final score. The statistical model of analysis for feed intake traits included age at first calving and herd-year-season of calving as fixed effects and random effects of animal and residual. The statistical model for type traits included fixed effects of age at first calving, days in milk and herd-round-classifier and random effects of animal and residual. Additionally, 13 (8 male and 5 female) phantom parent groups were fitted as covariates for all traits. Pedigree of animals with data was traced back 5 generations on both the male and female side to account for relationships among animals. Genetic parameters were estimated by fitting 5-trait animal models under restricted maximum likelihood using Wombat program. Estimates of heritabilities for DMI, NELI and CPI were 0.12, 0.13 and 0.13, respectively. Estimates of heritabilities of dairy strength, angularity, body depth, stature and final score were 0.31, 0.24, 0.30, 0.50 and 0.22, respectively. All phenotypic and genetic correlations between feed intake and type traits were positive. Genetic correlations between angularity and feed intake traits were strong and positive (0.60 to 0.65). Dairy strength showed strong positive genetic correlations (0.48 to 0.54) with feed intake traits . Both stature and body depth showed moderate positive genetic correlations (0.29 to 0.36) with feed intake traits. Angularity, dairy strength, stature and body depth may be useful for indirect selection of feed intake traits in dairy cattle.