Estimating the effect of hoof health on milk yield in British dairy cattle.

Lameness is a highly prevalent and economically important health problem in British dairy cattle. Previous studies have highlighted a delay between lameness onset and farmer detection. This lag, combined with the low sensitivity of clinical diagnosis, limits early intervention, thereby worsening both production and animal welfare outcomes. Notably, the negative effects of lameness can persist even after clinical recovery. Understanding the burden of health issues is essential for informed decision making at the farm level and beyond. This study quantifies the impact of hoof-health disorders on milk yield in British dairy cattle. Data were obtained from 6,050 cows across a nonrandom sample of 11 farms, including repeated daily milk yield records, totaling ∼2.1 million cow-days. A mixed linear model was developed to account for the time-dependent, correlated nature of milk yield data, using a first-order autoregressive correlation structure. An event study design allowed investigation of milk yield trajectories before and after clinical diagnosis. Farmer-reported data were used to identify hoof-related lameness events. After adjusting for mastitis, stage of lactation, parity, farm, season, and breed, cows with a hoof-health event produced on average 1.47 kg/d less milk than healthy cows. For severe cases, the average daily reduction reached 2.05 kg. The event study revealed that milk yield declines were detectable before clinical diagnosis and persisted after treatment. These findings underscore the impact of hoof-health disorders on dairy productivity and highlight the need for earlier detection as it could help farmers mitigate milk losses, reduce treatment costs, and enhance animal welfare.