title: Herd-level risk factors for hock injuries in freestall-housed dairy cows in the northeastern United States and California.
abstract: The aim of this study was to investigate the associations between management and facility design factors and the prevalence of hock injuries in high-producing dairy cows in 76 freestall herds in the northeastern United States (NE-US; Vermont, New York, Pennsylvania) and California (CA). One group of high-production multiparous cows was monitored on each farm, and data on management, facility and stall design, and the conditions of the hocks were collected. Focal cows [n=38 ± 3 (mean ± standard deviation)] were evaluated for hock injuries using a 3-point scale (where 1=healthy and 3=evidently swollen or severe injury). Measures associated with the proportion (logit-transformed) of cows having injuries (score ≥ 2) or severe injuries (score=3) at the univariable level were submitted to multivariable general linear models. In NE-US, overall hock injuries increased with the percentage of stalls with fecal contamination [odds ratio (OR)=1.26; 95% confidence interval (CI)=1.02-1.54, for a 10% increase], and with the use of sawdust as bedding (OR=3.47; CI=1.14-10.62), and decreased with deep bedding (i.e., at least 10 cm depth of any type of bedding; OR=0.05; CI=0.02-0.14), use of sand as bedding (OR=0.06; CI=0.02-0.15), bedding dry matter (DM) ≥ 83.9% (OR=0.08; CI=0.03-0.20), and access to pasture during the dry period (OR=0.17; CI=0.05-0.53). When these variables were submitted to a multivariable model, the presence of deep bedding was the only factor that remained significant, explaining 54% of the variation in overall injuries. Severe hock injuries increased with the use of automatic scrapers (OR=2.29; CI=1.11-4.71) and the percentage of stalls with fecal contamination (OR=1.14; CI=1.00-1.31, for a 10% increase), and decreased with sand bedding (OR=0.22; CI=0.10-0.49), deep bedding (OR=0.24; CI=0.11-0.52), bedding DM ≥ 83.9% (OR=0.28; CI=0.14-0.58), and access to pasture during the dry period (OR=0.42; CI=0.18-0.97). The final multivariable model, which explained 36% of the variation in severe hock injuries, included the use of automatic scrapers and deep bedding. In CA, stall stocking density (OR=1.41; CI=1.00-2.01, for a 10% increase) and poor bedding maintenance (OR=1.08; CI=1.01-1.16, for a 2.5-cm decrease in depth of deep-bedded stalls) were associated with an increase of overall and severe hock injuries, respectively. Deep-bedded and well-maintained stalls reduce the risk of hock injuries. Regional variation in risk factors for these injuries should be considered when formulating on-farm recommendations.
authors.affiliation: Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, V6T 1Z4, Canada.
authors.forename: A K
authors.initials: AK
authors.lastname: Barrientos
authors.forename: N
authors.initials: N
authors.lastname: Chapinal
authors.forename: D M
authors.initials: DM
authors.lastname: Weary
authors.forename: E
authors.initials: E
authors.lastname: Galo
authors.forename: M A G
authors.initials: MA
authors.lastname: von Keyserlingk
mesh_terms: D000827:Animal Welfare; D000818:Animals; D002140:California / Q000453:epidemiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology*; D003612:Dairying / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006799:Housing, Animal; D007794:Lameness, Animal / Q000453:epidemiology / Q000209:etiology; D009511:New England / Q000453:epidemiology; D012307:Risk Factors; D013643:Tarsus, Animal / Q000293:injuries*