The Effects of Claw Health and Bone Mineral Density on Lameness in Duroc Boars

SIMPLE SUMMARY: Lameness shortens the longevity and decreases the production efficiency of commercial herds. However, little research has been conducted on its causes in boars. In this study, we evaluated the prevalence of lameness from two aspects, claw health and bone health, using them for the first time to predict lameness in boars. The results show that claw lesions are widespread in boar populations, and swelling ankle (SWE) is significantly associated with lameness. In addition, lameness affected 22.86% of the boars in the osteopenia group. The prevalence of lameness was significantly higher in boars with osteopenia. Further analysis revealed that boar bone mineral density (BMD) was corelated to age, housing types, and serum Ca. Age had a convex quadratic curve relationship with bone mineral density, and the highest value was observed at the age of 43 months. More importantly, studies show that the bone mineral density of boars in individual pens was significantly higher than that of boars in individual stalls. Therefore, boars with different bone mineral density in different housing types may serve as a guide to improve boar lameness. It is necessary to improve the claw and bone health of boars in production to reduce the occurrence of lameness and improve the breeding value of boars. ABSTRACT: To investigate the effects of claw lesion types and bone mineral density on lameness in boars, the data of claw lesion score, gait score, and bone mineral density, measured by a Miniomin ultrasound bone densitometer, were collected from a total of 739 Duroc boars. Firstly, we discovered that the prevalence of claw lesions was as high as 95.26% in boars. The percentage of lameness of boars with SWE was higher than those with other claw lesions. Meanwhile, the results showed that the probability of lameness was higher in boars with lower bone mineral density (p < 0.05). Logistic regression models, including variables of boar age, body weight, serum mineral level, and housing type, were used to identify the influencing factors of bone mineral density in this study. The results found that bone mineral density increases with age before reaching a maximum value at 43 months of age, and begins to decrease after 43 months of age. Elevated serum Ca levels were significantly associated with an increase in bone mineral density (p < 0.05). Aside from the above findings, we also made an interesting discovery that boars in the individual pen model significantly increased bone mineral density compared to those in the individual stall model. In conclusion, claw lesions and bone mineral density were significantly associated with lameness. Age, serum Ca, and housing type are the potential influencing factors for bone mineral density in boars.