Cow- and herd-level risk factors for lameness in partly housed pasture-based dairy cows.

Discipline: lameness; Keywords: dairy cow, lameness, risk factor, pasture-based, selection.

Lameness is a major welfare and economic challenge in dairy farming and is commonly considered one of the three most costly diseases, with financial losses attributable to decreased milk production, fertility, treatment costs, and culling. Risk factor studies are critical to identify associations between potential risk factors and lameness, which could lead to future intervention studies. Previous risk factor analyses have focused on housed systems, rather than those where cows were grazed for the majority of the year and housed only for the winter period, such as in Ireland.  Therefore, the aim of an observational study by Dr N. Browne and colleagues was to identify a robust set of cow-level and herd-level risk factors for lameness in a pasture-based system, based on predictors from the housing and grazing periods. They have published their observations in the Journal of Dairy Science Volume 105, page 1418 to 1431 with the title: Cow- and herd-level risk factors for lameness in partly housed pasture-based dairy cows.

Ninety-nine farms were visited during the grazing period, and 85 farms were revisited during the housing period. At each visit, all lactating cows were scored for lameness (0 = good mobility, 1 = imperfect mobility, 2 = impaired mobility, 3 = severely impaired mobility), and potential herd-level risk factors were recorded through questionnaires and infrastructure measurements. Routine cow-level management data were also collected.

Both cow-level and herd-level risk factors were associated with lameness in the partly-grazed, partly-housed system. Cow-level risk factors included increased age and a positive inclination for lameness. Herd-level risk factors included smaller herd size and grazing platform, increased presence of digital dermatitis, presence of stones in gateways and slats on cow tracks, a tighter turn following milking, farmers who treated a higher proportion of their herd for lameness, and farmers who considered lameness to be a problem in their herd.

The authors concluded that farmers may benefit from a breeding program that places greater emphasis on lameness traits, and recommend that they should take measures to mitigate the effect of tight turns at the parlour exit and slats on the cow tracks, and removing stones from paddock gateways. Putting matting at the milking parlour exit and replacing slats on the cow tracks, should also be useful.