PREVALENCE AND TYPES OF BIRTH-DEFECTS IN ONTARIO SWINE DETERMINED BY MAIL SURVEY

Preweaning mortality in piglets constitutes a major loss to the swine industry. Congenital defects account for a small but significant propo rtion of these losses. To implement appropriate strategies to reduce s uch losses, it is necessary to identify the specific causes and their relative importance. Consequently, a mail survey of swine production i n Ontario was carried out to determine the prevalence and types of bir th defects. Statistical comparisons of the prevalence of overall defec ts were made between accurate and estimate records, breeds (cross vs. purebred), size of operation (number of sows) and geographic location. The mean litter size of 11 pigs born per sow was not significantly di fferent for those with accurate versus estimate records, but the diffe rence in the prevalence of defective pigs (live and dead) was signific ant (accurate 3.1% vs. estimate 4.1%). Splayleg (spraddleleg) was the most common defect. The next four defects for both groups were belly r upture, other rupture, ridglings and other, but not in the same rankin g. Purebred and small farm operations (<25 sows) had a significantly h igher prevalence of birth defects for estimated data only. Geographic location had no effect. Further work is required to determine whether recording prevalence of birth defects in Ontario swine will provide a useful monitor of environmental stress. The study provides a baseline for the prevalence and type of defects in Ontario swine.