Herd-level risk factors for lameness in freestall farms in the northeastern United States and California

The objective was to investigate the association between herd-level management and facility design factors and the prevalence of lameness in high-producing dairy cows in freestall herds in the northeastern United States (NE; Vermont, New York, Pennsylvania) and California (CA). Housing and management measures such as pen space, stall design, bedding type, and milking routine were collected for the high-producing pen in 40 farms in NE and 39 farms in CA. All cows in the pen were gait scored using a 1-to-5 scale and classified as clinically lame (score >= 3) or severely lame (score >= 4). Measures associated with the (logit-transformed) proportion of clinically or severely lame cows at the univariable level were submitted to multivariable general linear models. In NE, lameness increased on farms that used sawdust bedding [odds ratio (OR) = 1.71; 95% confidence interval (CI) = 1.06-2.76] and decreased with herd size (OR = 0.94; CI = 0.90-0.97, for a 100-cow increase), use of deep bedding (OR = 0.48; CI = 0.29-0.79), and access to pasture (OR = 0.52; CI = 0.32-0.85). The multivariable model included herd size, access to pasture, and provision of deep bedding, and explained 50% of the variation in clinical lameness. Severe lameness increased with the percentage of stalls with fecal contamination (OR = 1.15; CI = 1.06-1.25, for a 10% increase) and with use of sawdust bedding (OR = 2.13; CI = 1.31-3.47), and decreased with use of deep bedding (OR = 0.31; CI = 0.19-0.50), sand bedding (OR = 0.32; CI = 0.19-0.53), herd size (OR = 0.93; CI = 0.89-0.97, for a 100-cow increase), and rearing replacement heifers on site (OR = 0.57; CI = 0.32-0.99). The multivariable model included deep bedding and herd size, and explained 59% of the variation of severe lameness. In CA, clinical lameness increased with the percentage of stalls containing fecal contamination (OR = 1.15; CI = 1.05-1.26, for a 10% increase), and decreased with herd size (OR = 0.96; CI = 0.94-0.99, for a 100-cow increase), presence of rubber in the alley to the milking parlor (OR = 0.46; CI = 0.28-0.76), distance of the neck rail from the rear curb (OR = 0.97; CI = 0.95-0.99, for a 1-cm increase), water space per cow (OR = 0.92; CI = 0.85-0.99, for a 1-cm increase), and increased frequency of footbaths per week (OR = 0.90; CI = 081-0.99, for a 1-unit increase). The multivariable model included herd size, percentage of stalls containing fecal contamination, and presence of rubber in the alley to the milking parlor, and explained 44% of the variation of clinical lameness. Severe lameness increased with the percentage of stalls containing fecal contamination (OR = 1.23; CI = 1.06-1.42, for a 10% increase) and decreased with frequency of manure removal in the pen per day (OR = 0.72; CI = 0.53-0.97, for a 1-unit increase). The final model included both variables and explained 28% of the variation in severe lameness. In conclusion, changes in housing and management may help decrease the prevalence of lameness on dairy farms, but key risk factors vary across regions.