Date Full Report Received11/30/2003
Date Abstract Report Received07/24/2006
InvestigationInstitution: Fayetteville, University of Arkansas
Primary Investigator: Charles Maxwell, Jason Apple
Funded ByNational Pork Board
Age at weaning impacts growth performance as well as behavioral and immunological responses to management stressors, such as weaning and commingling after the nursery phase. A study conducted at the University of Arkansas evaluating the effects of weaning age and commingling after the nursery phase in wean-to-finish facilities on growth performance, immunological measurements, and behavioral observations, reported that older pigs were heavier throughout the nursery period. Body weight difference between younger and older pigs increased from 4.4 to 13.2 lb at the start and end of the nursery period, respectively. Younger pigs seemed to be more active (standing or walking vs. lying recumbent) than older pigs, and less immunogically developed, as evidenced by the increase in mortality rate observed for younger pigs during the nursery phase. However, pigs weaned at 14 d of age grew faster during the growing/finishing period and reached a common body weight (230 lb) four days sooner that pigs weaned at 21 d of age. It is unclear why the pigs weaned at 14 d of age that survived the nursery phase responded so robustly in the subsequent growing/finishing phase, although differences in immune system development may be the cause.