Genetic relationships between body condition score and reproduction

The objective of this study was to investigate the ge-netic relationship between body condition score (BCS) and reproduction traits for first-parity Canadian Ayr-shire and Holstein cows. Body condition scores were collected by field staff several times over the lactation in herds from Québec, and reproduction records (in-cluding both fertility and calving traits) were extracted from the official database used for the Canadian genetic evaluation of those herds. For each breed, six 2-trait animal models were run; they included random regres-sions that allowed the estimation of genetic correlations between BCS over the lactation and reproduction traits that are measured as a single lactation record. Analyses were undertaken on data from 108 Ayrshire herds an