Risk factors for lameness and hock injuries in Holstein herds in China.

The objective was to investigate the association between herd-level management and facility design and the prevalence of lameness and hock injuries in high-producing dairy cows on commercial freestall farms in China. Housing and management measures, such as stall design, bedding type, and milking routine were collected for the high-producing pen in 34 farms in China. All cows in the pen were gait scored using a 5-point scale, and evaluated for hock injuries using a 3-point scale. Measures associated with the proportion of clinically (score ≥3) or severely (score ≥4) lame cows, and the proportion of cows having at least a minor hock injury (score ≥2) or severe injury (score=3) at the univariable level were submitted to multivariable general linear models. The prevalence [mean ± SD (range)] of clinical and severe lameness were 31 ± 12 (7-51) and 10 ± 6% (0- 27%), respectively, and the prevalence of cows with at least a minor hock injury and with severe injuries was 40 ± 20 (6 - 95) and 5 ± 9% (0 - 50%), respectively. The prevalence of clinical lameness and severe lameness decreased with herd size (estimate=-0.35 ± 0.09% for a 100-cow increase for clinical lameness; estimate=0.15 ± 0.06% for a 100-cow increase for severe lameness). Prevalence increased with barn age >9 yr (estimate=12.73 ± 4.42% for clinical lameness; estimate=5.79 ± 2.89% for severe lameness). These 2 variables combined explained 49% of the variation in clinical lameness and 30% of the variation in severe lameness. The prevalence of all hock injuries and severe hock injuries decreased with deep bedding (estimate=-20.90 ± 5.66% for all hock injuries; estimate=-3.65 ± 1.41% for severe hock injuries) and increased with barn age >9 yr (estimate=16.68 ± 7.17% for all hock injuries; estimate=6.95 ± 1.75% for severe injuries). These 2 variables explained 52 and 58% of the variation, respectively. In conclusion, large variation existed across farms in prevalence of lameness and hock injuries. Changes in housing and management may help control the prevalence of lameness and hock injuries in the emerging dairy industry in China.