A genetic study of loser cows in Danish dairy herds

Abstract

Following the recent years' increase in herd size, the awareness of a group of cows with a generally lowered health and production level, the “loser cows,” has arisen in Denmark. The aim of this study was to estimate genetic correlations between the loser cow score, 305d protein yield and realized productive life (RPL) and inbreeding depression for the loser cow score. Estimation of genetic correlations and inbreeding depression was performed on 2644 first-lactation cows and 4914 multiple-lactation cows, respectively. We found no significant genetic correlation between the loser cow score and the inbreeding level or between the loser cow score and protein yield. However, the loser cow score was favorably correlated with RPL (−0.53). This implies that the prevalence of loser cows is neither a result of inbreeding depression nor an undesirable side effect of selecting for increased production.

Keywords:

• Genetic correlations
• inbreeding
• protein yield
• realized productive life

Acknowledgments

The authors thank Jørn Pedersen and Martha Bo Almskou from the Danish Knowledge Centre for Agriculture for providing data on protein yield and RPL as well as Anders Christian Sørensen from the Department of Molecular Biology and Genetics for valuable help with the inbreeding analyses.