Associations between foot lesions and carcass traits in young bulls reared indoors

Even if painful foot lesions are frequent in indoor-finished young bulls, little is known about their economic impact. Previous research has primarily focused on their effect on average daily gain, but their potential impact on carcass weight and quality could further increase their economic cost and relevance to producers. This study aimed to investigate the relationships between foot lesions and key carcass characteristics, namely carcass weight, conformation, fat cover, and age at slaughter, in French beef and dairy young bulls. Postmortem data were collected from 2 089 animals across four slaughterhouses during two seasons in 2023. Each bull underwent a comprehensive foot examination, and lesion annotation was assessed using standardised criteria. Slaughter data, including carcass weight, EUROP muscle development scores, fat cover scores, and age at slaughter, were obtained from slaughterhouse records. Mixed multivariable linear and mixed ordinal logistic regression models were used to assess associations between specific foot lesions and carcass traits, adjusting for breed and other confounding factors, and including farm as a random effect to account for clustering. Results revealed that certain lesions, such as interdigital phlegmon and bulb ulcer, were negatively associated with carcass weight, suggesting a detrimental effect on growth. In contrast, heel horn erosion and various forms of sole and white line haemorrhages were associated with higher carcass weight and better conformation scores. For sole and white line haemorrhages, carcass weight increased progressively with lesion severity, further supporting the hypothesis that heavier animals may be more prone to developing these types of lesions. Heel horn erosion was also the only lesion significantly associated with higher slaughter age. The evidence for associations between foot lesions and fat cover, as well as between digital dermatitis and carcass traits, was inconclusive. Breed also significantly influenced carcass traits, with beef-specialised breeds generally achieving higher carcass weights and conformation scores compared to dairy-origin or crossbred animals. These findings suggest that foot lesions, while sometimes detrimental, may also reflect complex interactions between growth dynamics and foot health. They underscore the need for integrated management strategies that consider foot health not only as a welfare issue but also as a factor influencing or related to carcass performance and economic returns in beef systems.