Slaughterhouse examination of culled sows in commercial pig herds

A proper culling policy in sow herds is a prerequisite to maintain a stable parity profile of the breeding animals and to maintain consistent production. This study investigated reasons for culling of 502 sows from 7 commercial pig herds and examined the reproductive tract of these sows by macroscopical, bacteriological and histopathological examination. Associations between all three examinations were statistically analysed. More than 50% of the sows was culled because of reproduction failure, while old age was the second most common reason (23%). Approximately 75% of the examined uteri were visually normal. Purulent exudate was detected in 18% of the animals. No abnormalities were found in 54% of the ovaries, whereas 28% showed inactivity. Sixty-two percent of the uteri were bacteriologically positive, with Escherichia coli (18%) being the most frequently isolated. Histologically, 52% of the uteri showed mild to severe inflammation. From the uteri with endometritis based on visual inspection and histology, 26% and 30% was bacteriologically negative, respectively. The presence of bacteria showed a slight agreement with macroscopical (κ=0.14, p=0.04) and histopathological endometritis (κ=0.18, p=0.04). No agreement was found between macroscopical and histopathological lesions (κ=−0.06, p>0.05). Major differences were found between herds for all parameters. In conclusion, sows are mostly culled because of insufficient reproductive performance, and many of the culled sows show endometritis lesions. Histopathology appears to be more sensitive than visual inspection.