A cross-sectional study to collect risk factors associated with stillbirths in pig herds.

The aim of this study was to identify risk factors for stillborn piglets at herd level in commercial pig herds. A written questionnaire, containing semi-open questions directly or indirectly related to stillborn piglets, was sent to 250 randomly selected pig herds (>150 sows) in northern Belgium. In total 111/250 questionnaires were returned (response rate of 44.4%) and 107 were valid for analysis. The average reported frequency of stillbirth was 7.5% (S.D. 2.8%). The relationship between risk factors and stillbirths was evaluated with a generalized linear effects model with the percentage of stillborn piglets as outcome variable. Type of breed used on the farm was significantly (P<0.01) associated with the percentage of stillborn piglets. A high temperature in the farrowing unit (> or =22 degrees C compared to <22 degrees C) was associated with significantly (P<0.01) more stillbirths, whereas showering sows with warm water before parturition resulted in significantly less stillbirths (5.8%) than no showering (7.7%) (P<0.01) and was not significantly different from showering with cold water (7.0%) (P=0.26). When supervision of farrowing was performed occasionally, significantly more stillbirths (8.1%) were observed in comparison with no attending to farrowing (6.5%) (P<0.01) or frequent supervision of farrowing (6.9%) (P<0.01). Significant interactions were found between breed and showering sows prior parturition or supervision of sows at parturition, and between temperature in the farrowing unit at parturition and showering procedure of the sows. In conclusion, this study has clearly demonstrated that breed is a major factor involved in the frequency of stillbirth. Additionally, some management practices before or at parturition may reduce the number of stillborn piglets.