| Summary: | The objective of this thesis was to investigate housing and management risk factors associated with the prevalence of hock injuries in freestall herds (n = 76) in two areas of intensive dairy production, Northeastern US (NE-US) and California (CA). One group of high-production multiparous cows (n = 38) was monitored for hock injuries on each farm and data on management, facility and stall design were collected. Risk factors associated with the overall proportion of cows having injuries or severe injuries 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 (OR = 1.26; CI = 1.02 to 1.54, for a 10% increase), and with the use of sawdust bedding (OR = 3.47; CI = 1.14 to 10.62), and decreased with deep bedding (OR = 0.05; CI = 0.02 to 0.14), sand bedding (OR = 0.06; CI = 0.02 to 0.15), bedding DM ≥ 83.9% (OR = 0.08; CI = 0.03 to 0.20), and access to pasture during the dry period (OR = 0.17; CI = 0.05 to 0.53). In the multivariable model, only the presence of deep bedding remained significant. Severe hock injuries increased with the use of automatic scrapers (OR = 2.29; CI = 1.11 to 4.71) and the percentage of stalls with fecal contamination (OR = 1.14; CI = 1.00 to 1.31, for a 10% increase), and decreased with sand bedding (OR = 0.22; CI = 0.10 to 0.49), deep bedding (OR = 0.24; CI = 0.11 to 0.52), bedding DM ≥ 83.9% (OR = 0.28; CI = 0.14 to 0.58), and access to pasture during the dry period (OR = 0.42; CI = 0.18 to 0.97). The multivariable model included the use of automatic scrapers and deep bedding. In CA, stall stocking density (OR = 1.41; CI = 1.00 to 2.01, for a 10% increase) and bedding concavity (OR = 1.08; CI = 1.01 to 1.16, for a 2.5-cm decrease) were associated with an increase of hock injuries. In general, deep-bedded and well-maintained stalls significantly reduced the risk of hock injuries.
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