Calving traits and their relationship with production, conformation and workability traits in Holstein-Friesian cows

It has been well established that the genetic correlations between calving traits are positive, ie longer gestation lengths are associated with increased calf size, greater incidence of calving problems and higher calf mortality. However, correlations of calving traits with other traits could be of economic importance, indeed some breeding companies market bulls for calving ease on the basis of low liveweight Australian Breeding Values (ABVs). We found that there was an association between calving ease ABV, fertility and liveweight, (large liveweight is associated with increased calving difficulty and reduced fertility), and increased calf size, greater liveweight and reduced fertility were all associated with each other. However, increased gestation length was not associated with increased mature cow liveweight, even though it was associated with larger calf size.