Effect of Weaning Age and Commingling After the Nursery Phase on Growth Performance, Mortality Rate, and Behavioral Indicators of Welfare1

摘要

Age at weaning, as well as behavioral responses to management stressors, such as weaning and commingling after the nursery phase, impacts growth performance. This study evaluated the effects of weaning age and commingling after the nursery phase in wean-to-finish facilities on growth performance, mortality rate, and behavioral observations. Atotal of 216 pigs were weaned at 14 or 21 d of age, divided into older and younger age groups (108 pigs/group) and penned 12 pigs/pen. Pigs were fed common Phase1 (d 0 to 14) and Phase 2 (d 14 to 34) diets during the nursery phase. At the end of the nursery, one-half of the pigs in each age group were removed, re-randomized, and commingled for the finishing phase, whereas the other half of the pigs remained intheir original pens. Pigs were fed a four-phase common diet with transitions at 100, 150, and 198 Ib. The study was terminated when pigs averaged 235 Ib. Pigs weaned at an older age were heavier throughout the nursery period; and the BW difference between younger and older pigs increased from 4.4 Ib at the start to 13.2 Ib at the end of the nursery period. Younger pigs seemed to be more active (standing or walking vs. lying recumbent) than older pigs. However, pigs weaned at 14 d of age grew faster during the growing/finishing period and reached a common body weight (230 Ib) 4 days sooner than older pigs. In conclusion, pigs weaned at 14 d of age grew slower than pigs weaned at 21 d of age during the nursery phase; however, younger pigs gained more than older pigs later in the finishing period. Commingling of pigs following the nursery phase did not affect ADG; however, the effects of commingling on ADF1 were dependent on age at weaning, in that commingling decreased feed intake only in pigs weaned at 21 d of age.