Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2003
Publication Date: 9/2/2003
Citation: KLINDT, J.M. INFLUENCE OF LITTER SIZE AND CREEP FEEDING ON PREWEANING GAIN AND INFLUENCE OF PREWEANING GROWTH ON GROWTH TO SLAUGHTER IN BARROWS. JOURNAL OF ANIMAL SCIENCE. 2003. V. 81. P. 2434-2439.
Interpretive Summary: Pork producers have long been advised to employ management practices that would maximize weight of piglets at weaning. However, much of the data supporting this advice was obtained with weaning at ages older, 28 days or more, than the current standard, 14 to 21 days, some as early as seven days of age. Also, slaughter weights have increased and weaning weight, as a proportion of slaughter weight, has declined from about 15% to less than 5%. This study investigated the effect of litter size and availability of supplemental, creep feed on preweaning growth rate, and the effect of preweaning growth rate on postweaning growth and yield of marketable pork. The greater the number of pigs in a litter, the less their growth rate. Providing creep feed increased growth rate of piglets in the larger sized litters, litters in which availability of milk was limited. Birth weight, preweaning growth rate, and weaning weight were positively related to postweaning growth rate and yield of marketable pork. The combination of birth weight, preweaning growth rate, and their interactions were superior to weaning weight as a predictor of postweaning growth rate and yield of marketable pork. Results indicate that management practices that increase preweaning gain, e.g., creep of the piglets during nursing or enhanced milk production by the sow will, decrease time to market weight and increase yield of marketable pork.
Technical Abstract: Objective of this study was to assess importance of birth-to-weaning average daily gain (ADG) as a determinant of weight at a final age and yield of marketable pork. Newborn pigs were cross-fostered to create assigned litters of 4 through 14 pigs/litter. Creep feed was offered to pigs from five d of age or during last two days before weaning at 13 to 20 d, average = 17 d. Treatments were imposed to create variation in birth-to-weaning ADG. Data was obtained from 195 barrows that were slaughtered at an average age of 170 d, weight of 109 kg. Carcass dissection data was recorded. All traits measured were influenced (P < 0.01) by birth dam, and all, except fat trimmed from four lean cuts, were influenced (P < 0.10) by birth weight. Birth-to-weaning ADG and weaning weight were not influenced (P > 0.38) by the main effect of creep feeding treatment; however, fit of linear, quadratic, and cubic contrasts was different between creep feeding treatments. Examination of data reveals a positive influence of creep feeding from five d of age on birth-to-weaning ADG and weaning weight in larger size litters. Importance of 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, R2s for models ranked birth weight < birth-to-weaning ADG < d-17 weaning weight < birth weight + birth-to-weaning ADG. Results indicate positive relationships between birth-to-weaning ADG and measures of postweaning growth and carcass yield, suggesting management practices that increase birth-to-weaning ADG may be advantageous in pork production. However, these data do not allow evaluation of costs and benefits of management changes that would increase birth-to-weaning ADG, and thus, increase postweaning growth rate.