Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/1996
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Effect of thermal environment on immunophysiology of preweaning pigs is not clear. The main objective of this study was to evaluate the capability of preweaning pigs housed in two different thermal environments to respond to an acute immunological challenge. Sows with pigs were housed in environ- mental chambers in either a cycling hot (27-32 deg C) or cool (21 deg C) thermal environment. At 28 d of age, the pigs were peripherally challenge (ip) with 150 ug/kg of E. coli lipopolysaccharide (LPS) or with saline as a control. Rectal temperature (Tr) was measured at the time of injection (0 h), and 1, 2, and 3 h postinjection. Behavioral responses were monitored during the same time period. At 3 h after injection, pigs were sacrificed and blood samples were collected to determine serum levels of TNF-alpha. Average baseline Tr (0 h) was significantly higher (P<0.05) in pigs housed in the hot environment (39.61 +/ 0.05 vs 39.16 +/ 0.16 deg C). The LPS injection induced a febrile response (P<0.05) in pigs housed in the hot environment. Average Tr in the LPS-injected animals from the cool environment did not significantly change, although there was a tendency toward somewhat reduced temperature at 2 and 3 h postinjection. All pigs injected with LPS developed sickness behavior characteristic to an acute-phase response, such as vomiting, diarrhea, lethargy, somnolescence, anorexia, and decreased general activity. Serum levels of TNF-alpha, a cytokine regarded as one of the main endogenous mediators of an acute-phase response, were significantly elevated (P<0.05) in pigs injected with LPS. There was no significant effect of environmental temperature on TNF-alpha levels. These data indicate that thermal environment may significantly impact health of immunologically challenged preweaning pigs.