Skin lesions and callosities in group-housed pregnant sows: Animal-related welfare indicators

An on-farm investigation of 55 herds of pregnant sows housed in various group-housing systems was carried out. Management factors, pen design and abnormalities of the integument of 1177 pregnant sows were examined. The arithmetic mean of injured body regions was 1.49 as a total value per sow, 0.94 on the front part of the body and 0.56 on the rear part of the body. Group size, the design of the feeding place and area per sow (within stable groups) showed a significant influence on the extent of lesions. The limbs displayed 3.53 callosities on average per sow. In littered systems the prevalence of callosities was significantly lower. Callosities were positively correlated with decubital lesions. This investigation showed that lesion patterns on the skin do act as indicators of welfare. An adequately designed feeding area, good management and the maintenance of groups with established social ranks can minimise fighting. A smooth lying area and the opportunity to move around reduce the incidence of callosities.