title: Influence of litter size and creep feeding on preweaning gain and influence of preweaning growth on growth to slaughter in barrows.
abstract: 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 birth-to-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-to-weaning ADG and weaning weight in larger size (> 8) litters. Importance of the independent variables birth weight, birth-to-weaning ADG, weaning weight, and birth weight plus birth-to-weaning ADG in determination of measures of postweaning growth and yield of marketable pork were examined by step-down regression analysis. Initial models included the linear and quadratic effects of the independent variables. In general, R2 for models ranked birth weight < birth-to-weaning ADG < d-17 weaning weight < birth weight + birth-to-weaning ADG. The R2 of models for BW at 170 d of age were 0.11 (P < 0.01) using birth weight as the independent variable, 0.16 (P < 0.01) using birth-to-weaning ADG, 0.19 (P < 0.01) using d-17 weaning weight, and 0.21 (P < 0.01) using birth weight + birth-to-weaning ADG. The model for effect of birth-to-weaning ADG on BW at 170 d of age indicated that a 10-g advantage in birth-to-weaning ADG produced a 0.94-kg advantage in BW at 170 d of age. Positive relationships (P < 0.05) between birth-to-weaning ADG and measures of postweaning growth and carcass yield suggest management practices that increase birth-to-weaning ADG may be advantageous in pork production.
authors.affiliation: USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933, USA. klindt@email.marc.usda.gov
authors.forename: J
authors.initials: J
authors.lastname: Klindt
mesh_terms: D000375:Aging / Q000502:physiology*; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development; D001835:Body Weight; D004435:Eating; D005260:Female; D008098:Litter Size / Q000502:physiology*; D008297:Male; D008460:Meat / Q000592:standards*; D013552:Swine / Q000254:growth & development*; D013997:Time Factors; D014886:Weaning; D015430:Weight Gain / Q000502:physiology*