Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2001
Publication Date: N/A
Interpretive Summary: During the last five years, we have been evaluating the influence of birth on subsequent growth in the young pig. Previous work in our laboratory has demonstrated that the stress and trauma associated with the natural birth process is necessary in order to assure optimal postnatal growth and performance. The objective of this study was to determine if administration nof an additional amount of stress hormone at birth would alter postnatal growth. For this study we used forty pigs which were injected with either sterile saline or dexamethasone (a potent synthetic stress hormone) within one hour of birth. The growth of these pigs was monitored during the first 18 days of life while the pigs were still nursing the sows. Results from this study demonstrated that growth rate was enhanced by more than 12 percent in those pigs which received the dexamethasone treatment within one hour of birth. Additionally, the hormones which are typically associated with postnatal growth, growth hormone and the insulin-like growth factors, were altered in the dexamethasone treated pigs in a manner which was consistent with the increased growth observed in these pigs. Given that early postnatal growth is highly correlated with growth throughout the pig's life, increasing early neonatal growth could potentially result in significant savings for the swine industry with regard to feed costs, facility costs, etc.
Technical Abstract: The objective of this study was to determine if dexamethasone (Dex; a potent synthetic glucocorticoid) treatment at birth would alter postnatal growth in neonatal pigs. Forty crossbred pigs were injected i.m. with either sterile saline (Cont; n=10 males and 10 females) or Dex (1 mg/kg; n=10 males and 10 females) within 1 hr of birth. All pigs remained with their respective dams until 18 d of age. Body weights were recorded weekly and on d 18. On d 17, all pigs were non-surgically fitted with an indwelling jugular catheter. On d 18, all pigs were placed in individual pens for serial blood collection. Birth weights (1.53 +/ .04 kg) did not differ between birth treatments or sex classes. A time by treatment effect was detected (P<0.007) for body weight such that those pigs which received Dex at birth had the greatest body weights during the 18-d period. Average daily gain was increased (P<0.017) by 12.2% in those pigs which received Dex at birth. Serum concentration of IGF-1 was influenced by both treatmen (P<0.0001) and sex class (P<0.013). In the male pigs, Dex increased (P=0.0041) serum concentration of IGF-1 by 47% as compared to Cont male pigs, whereas in the females, Dex increased (P<0.011) serum concentration of IGF-1 by 34% as compared to Cont female pigs. Dex treatment reduced (P<0.002) serum IGF-2 by 12.8%. Serum concentration of IGFBP-3 was influenced by both birth treatment (P<0.007) and sex class (P<0.002) such that Dex treatment increased serum IGFBP-3, and higher concentrations of IGFBP-3 were observed in boars as compared to gilts. These data suggest that the early neonatal period may be an opportune time to alter physiological factors which influence growth in swine.