Scores for clinical lameness from two separate studies were combined, and genetic parameters were estimated based on linear and threshold models. Cows were from 24 herds in Minnesota, Wisconsin, and Virginia. To evaluate clinical lameness, cows were observed walking and were assigned a score between 0 and 4 (where 0 = no observable problems to 4 = inability to walk). Data included 1624 records on 1342 cows. The models included fixed effects of herd visit, parity, and stage of lactation. Random effects were additive genetics, permanent environment to account for repeated records, and residual. Estimates of heritability were 0.10 and 0.22 from the linear and threshold models, respectively. The correlation between ETA from linear and threshold models based on all animals was 0.974. Deregressed ETA of sires and REML were used to estimate genetic correlations between clinical lameness and conformation traits. Among the type traits, foot angle, rear legs (rear view), and rump width had strongest associations with clinical lameness; absolute values for genetic correlations between these traits and clinical lameness were approximately 0.65. Low foot angle, hocking in, and wide rumps were associated with increased clinical lameness. Correlations with strength and body depth ranged from 0.20 to 0.43, indicating that heavier cows were more prone to clinical lameness.
Bibliographical noteFunding Information:
A number of people contributed to this research. We first thank the producers for allowing the collection of data for this project. We also thank Jerry Steuernagel from Minnesota DHIA and Ken Butcher from the Dairy Records Processing Center in Raleigh, North Carolina for providing production and pedigree information for the cows in the study. We also thank Les Hansen and John Galgowski for providing DHIA information for research herds in Minnesota and Wisconsin, respectively. We thank Paul VanRaden and Ryan Starkenberg from the USDA for providing us with pedigree information for the bulls with daughters in the study. We also recognize Tom Lawlor from the US Holstein Association for providing ETA for type traits of the bulls. We thank Eildert Groeneveld, Agust Sigurdsson, Georgios Banos, Larry Schaeffer, and Luc Janss for use of their software and Geert Jongert for data processing. Finally, we thank the Cattle Breeders Research Council of Canada for their financial support of this research.
- Clinical lameness
- Genetic correlation