Development of a group-adapted housing system for pregnant sows : a field study on performance and welfare aspects
A Sow-Welfare-Optimized-Feeding (SWOF) system with group-adapted ad libitum liquid feeding was developed to ensure that both optimal nutritional and behavioral needs are met in grouphoused pregnant sows. This system comprises functional areas and allows sows to have either a low- or high-energy diet according to their current weight in relation to their parity. This field study aimed to investigate how this new system influences sows’ body weight, health status (lameness), aggression parameters (integument injuries, vulva injuries, and displacements at the trough), feed intake rhythm, and litter performance. In parallel, these parameters were also recorded in the existing system (group-housed sows restrictively fed a dry diet). In the SWOF system, the probability of displacements at the trough and occurrence of vulva injuries were reduced, whereas sows could follow a natural biphasic feed intake rhythm. Though lameness scores and litter performance were not affected, lower body weights and more integument injuries were, however, observed. Yet, results can only partially be attributed to the feeding system per se due to confounding effects such as management practices and group size differences (larger dynamic group vs. stable group). Hence, the SWOF system seems promising with regard to animal welfare but remains to be further validated.