Summary and Implications
A multiple trait animal model was implemented to study the direct genetic and maternal genetic relationship among four traits, dystocia (DYS), perinatal mortality (PM), birth weight (BW) and gestation length(GL), expressed at the birth of a calf. The sign and magnitude of genetic correlations among calving traits demonstrates the need to use multi-trait animal models for genetic evaluation of animals for calving performance. Adequate information exists to begin developing a calving performance index. This index will enable breeders of dairy cattle to optimize the health and well-being of replacement animals and reduce the incidence of dystocia and perinatal mortality.
Iowa State University
Johanson, James and Berger, P. Jeffrey
"Estimates of Genetic Parameters for Calving Performance from Designed Selection Studies,"
Animal Industry Report:
AS 653, ASL R2197.
Available at: http://lib.dr.iastate.edu/ans_air/vol653/iss1/23