Severe vulva biting in gestating sows; a case report

Introduction: Vulva biting is a welfare impeding behaviour especially seen in group housed sows fed with electronic sow feeders (ESF’s). At a 1200 head SPF sow farm in the Netherlands, where 800 sows were housed in one dynamic group with 14 ESF’s, periods with severe vulva biting were observed. This study aims to describe the incidence of vulva biting and associations with parity and production stage as well as the diagnostic process to detect potential causes and improvements in the farm.Materials & methods: Continuous video capture of the area near the entrance of 5 feeding stations was analysed in order to determine when, where and which sow(s) performed vulva-biting and what the possible causes are. Periods in which less than four animals were waiting to enter the ESF were excluded from the analysis. For a two-day period, every hour during seven minutes, vulva biting, and related behaviours and clinical signs, were quantified. Results & conclusions: Damaged vulvas were observed in 69% of the gestating sows, but not in gestating gilts. Biting was performed in the area near the entrance and in the feeding station. Vulva biting was only seen just after a new feeding day was started, particularly in the first nine hours. The analysis showed that overcrowding, residual feed (due to no water supply and or feed disposal rate ) in the feeding station and malfunction of the entrance gate were evident risk factors which contributed to vulva biting. The suspicion was raised that biting was performed by the older and thus dominant sows. We did not observe gilts vulva biting. Video analyses showed pivotal to diagnose the problem and define interventions, such as removal of old sows, adequate repair of ESF and prevention of overcrowding.