Hock injury prevalence and associated risk factors on organic and nonorganic dairy farms in the United Kingdom.

The presence of hock injury was assessed in the milking herds of 80 dairy farms (40 organic, 40 nonorganic) across the United Kingdom. A wide range of information on farm management and husbandry was gathered via interview to assess the factors contributing to hock damage for all 80 farms, and a comprehensive building appraisal was conducted for 40 farms visited during the winter housing period. The prevalence of hock lesions was lower on organic compared with nonorganic farms (37.2 vs. 49.1%). Prevalence of hock damage was greater in the spring than fall (59.9 vs. 21.6%) and cows housed in free-stalls had a greater prevalence of hock lesions than those housed on straw (46.0 vs. 25.0%). Prevalence of hock damage increased with lactation number. In the analysis of fall/spring data, the age first mated, herd biosecurity, duration of summer grazing, and cow milk yield were significant factors relating to herd hock damage. Larger herds had a greater proportion of cows with hock swellings. Farms with a shorter calving interval had more cows with hock swellings. Factors relating to housing conditions that were positively associated with the prevalence of hock damage were low feed face space per cow, inferior passageway cleanliness, low total standing area per cow, and the type of bedding added to the free-stall. To assess whether free-stall versus straw-pen or organic versus nonorganic farms had different sets of risk factors, the data were reanalyzed for these types separately. For the straw-pen farms a high culling rate was associated with more hock damage. Within nonorganic farms, the length of summer grazing was significant, with longer periods meaning less hock injury. The prevalence of hock injuries on many UK farms, both organic and non-organic, exceeded levels that are deemed acceptable for cow comfort. Efforts are needed to improve housing standards to reduce the prevalence of hock injury and consequently improve cow welfare.