Effect of piglet birth weight on survival and quality of commercial market swine

Abstract

The objective of this study was to determine the effect of individual piglet birth weight on mortality and pig quality in a U.S. commercial production system. Pigs used in this study were farrowed from Large White × Landrace sows ( n = 463) bred to Duroc boars during a 4 week period at a commercial sow farm. Within 24 h of birth, all pigs (born alive = 5727 and stillborns = 513) were weighed and individually indentified. A portion of pigs (16.7%) were cross-fostered to reduce litter size variation during lactation. Individual mortality was recorded daily during the suckling phase. Pigs were weighed 2 days prior to weaning (18.7 ± 2.1 days of age), finisher placement (74.8 ± 1.9 days of age), and 16 weeks into finishing (172.8 ± 1.8 days of age). During BW collections, an inventory of all live pigs was conducted, and pigs were given a quality score based on visual evaluation of BW and health (3 = healthy pig; 2 = slightly small and/or slightly unthrifty; 1 small and/or unthrifty). Survival was analyzed for 4 distinct time periods (prenatal, pre-weaning, nursery phase, and finishing phase). Data were analyzed using a logit (survival) or cumulative logit (quality score) function. Birth weight linear effects on prenatal, pre-weaning, and nursery survival as observed mortality probability increased as birth weight decreased. However birth weight did not impact the likelihood of survival during finishing. As birth weight decreased, the likelihood of pigs being poorer quality, quality score (1 or 2), at weaning, finisher placement, and 16 weeks into finishing, increased. As birth weight increased the likelihood of a pig being full value at the end of the finishing phase increased. Reduced individual piglet birth weight, was associated with reduced pig quality and likelihood of prenatal, pre-weaning, and nursery survival. Because of the negative impact of birth weight on pre-weaning and nursery survival and pig quality in finishing, as birth weight decreased pigs were less likely to be full value at harvest.