Influence of litter size and creep feeding on preweaning gain and influence of preweaning growth on growth to slaughter in barrows1,2

The importance of birth-to-weaning average daily gain as a determinant of weight at a final age and yield of marketable pork was investigated. Treatments were imposed to create variation in birthto-weaning ADG independent of birth weight. Newborn pigs were cross-fostered to create litters of four through 14 pigs/litter. Creep feed was offered to pigs from 5 d of age or during last 2 d before weaning at 13 to 20 d (average = 17 d). Growth rate and carcass dissection data were obtained from 195 barrows that were slaughtered at an average age of 170 d (SD = 7.5), weight of 109 kg (SD = 10.5). All traits measured were influenced by birth dam and sire (P < 0.01). Quadratic and cubic effects (P < 0.09) of litter size on birth-to-weaning ADG and weaning weight were different between the creep feeding treatments. Data revealed a positive influence (P < 0.04) of creep feeding from 5 d of age on birth-toweaning ADG and weaning weight in larger size (>8) litters. Importance of the independent variables birth weight, birth-to-weaning ADG, weaning weight, and