The influence of feed delivery and feeding patterns during gestation on reproductive outcomes for sows

Mid-parent breeding values and outcomes from 6126 mating (4998 farrowing) events and accompanying feed-related traits, derived from feeding events recorded during gestation, were used to investigate the associations between these factors with reproductive outcomes for commercial sows. Variability in genetic merit for piglet birth weight had undesirable consequences for premature sow removal (REM35). Sows in the highest quintile for missed feeding events (> 24 hours between meals) recorded over 90 days had both lower farrowing rate (97.2% vs 97.9 - 99.2%) and increased REM35 (12% vs 7 - 9.5%) compared to the rest. Results from the present study demonstrated that when feeding during gestation did not accommodate variation in litter size and body weight amongst sows, performance of the "average" sow with respect to litter size was favoured. While heritability of intake under restricted feed delivery was zero, variability in litter size alone created heritable variation (h2 ~ 0.05) in actual feed requirement, and therefore the deviation in actual intake from requirement. Reproductive outcomes for commercial sows, and the retention of genetically superior sows for reproductive traits, might be better optimised if gestational feeding was better adapted to sow phenotypes.