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Title: THE EFFECTS OF THERMAL ENVIRONMENT AND SPRAY-DRIED PLASMA ON THE ACUTE-PHASE RESPONSE OF PIGS CHALLENGED WITH LIPOPOLYSACCHARIDE

Author
item FRANK, JASON - ANIMAL SCIENCE-UNIV OF MO
item Carroll, Jeffery - Jeff Carroll
item ALLEE, GARY - ANIMAL SCIENCE-UNIV OF MO
item ZANNELLI, MIKE - ANIMAL SCIENCE-UNIV OF MO

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2003
Publication Date: 5/20/2003
Citation: Frank, J.W., Carroll, J.A., Allee, G.L., Zanelli, M.E. The effects of thermal environment and spray-dried plasma on the acute-phase response of pigs challenged with lipopolysaccharide. Journal of Animal Science. 2003. v. 81. p. 1166-1176.

Interpretive Summary: It has been known for several years that diets for weaning pigs that contain spray-dried plasma (SDP) improve growth performance. Interestingly, the use of SDP to improve pig performance in conventional, on-farm nurseries is more effective than in environments with a lower pathogen load. The improved performance of pigs fed SDP is believed to be related to the immunoglobulin fraction of this feedstuff. The enhanced performance of pigs consuming SDP may also be the result of the pigs being more immunologically naïve than pigs consuming diets with no SDP. We have previously demonstrated that pigs fed SDP exhibit greater immune stimulation when challenged with the bacterial endotoxin, lipopolysaccharide (LPS). In addition to SDP, we have also demonstrated that cold stress influences the immune response in neonatal pigs. Therefore, this study evaluated the effects of feeding diets with or without SDP in a thermal neutral or cold environment on the acute phase response associated with an immune challenge in nursery pigs. Overall, our results indicated that there were no consistent interactions between feeding SDP and thermal environment. Pigs consuming diets containing SDP and subsequently challenged with LPS responded with elevated serum concentrations of cortisol and cytokines compared to pigs fed diets with no SDP. Additionally, housing pigs in a cold environment increased the basal concentrations of stress hormones, and when challenged with LPS resulted in elevated serum and tissue mRNA levels of the cytokines associated with an acute phase immune response. From these results, we conclude that rearing pigs in thermal neutral environments not only improves the growth performance, but it also reduces the opportunity for bacterial infection to occur. When pigs are housed under conditions of cold stress, feed intake and feed to gain ratios increase, while the ability of the animal to combat bacterial disease is inhibited. Additionally, feeding spray-dried plasma can provide enhanced growth performance of weaned pigs maintained in many different environmental conditions. However, if pigs consuming spray-dried plasma are exposed to challenges that bypass intestinal immune protection, they may become hyper-responsive immunologically and demonstrate reductions in growth performance.

Technical Abstract: Forty barrows (TR4 x C22) were weaned at 17 d of age (initially 6.27 +/- 0.30 kg) and housed two pigs/pen in a thermal neutral environment (TN: constant 26.7 degrees C) and fed diets with or without 7% spray-dried plasma (SDP). On d 7, one pig/pen was moved into a cold environment (CE: constant 15.6 degrees C). Pigs were fitted with jugular catheters on d 11. The following day, 16 pigs/environment (8 pigs/dietary treatment) were challenged with 75 ug/kg of BW of lipopolysaccharide (LPS). Blood samples were collected over a 4.5-h period. Pigs were then sacrificed and tissue samples harvested for mRNA analysis. From d 0 to 7 pigs fed SDP diets had a lower gain to feed ratio than pigs fed no SDP (533 +/- 14 vs 585 +/- 17 g/kg; P < 0.03). Pigs housed in the CE consumed more feed and had lower gain to feed ratios than pigs housed in TN from d 7 to 11 (P < 0.001). There were no environment by diet interactions from d 7 to 11 (P > 0.78). Basal concentrations of serum ACTH and cortisol were lower in the TN pigs compared to the CE pigs (P < 0.001). Pigs fed diets without SDP had lower serum cortisol concentrations over the 4.5-h period compared to the pigs fed SDP (time x diet, P < 0.001). Serum concentrations of tumor necrosis factor-alpha (TNF) were highest for pigs consuming SDP in the CE, while there were no differences among the other treatments (time x diet x environment, P < 0.02). Pigs housed in the CE had higher serum interleukin-1 beta (IL-1) and interleukin-6 (IL-6) compared to TN pigs (P < 0.001). Furthermore, pigs consuming SDP also had slightly higher serum IL-1 concentrations (P < 0.10) and significantly higher IL-6 concentrations compared to the pigs fed no SDP. Pigs fed SDP had 9% lower liver and 13% lower thymus mRNA expression of TNF than pigs consuming no SDP (P < 0.06). Liver IL-1, IL-6, and LPS binding protein mRNA were higher in the CE compared to TN (P < 0.03, P < 0.001, and P < 0.05, respectively). In addition, spleen TNF and IL-6 mRNA levels were higher in the CE (P < 0.03 and P < 0.01, respectively). Overall there were no consistent interactions between feeding SDP and thermal environment. Pigs consuming diets containing SDP and subsequently challenged with LPS responded with elevated serum concentrations of cortisol and cytokines compared to pigs fed diets with no SDP. Housing pigs in a CE increased the basal concentrations of ACTH and cortisol, and when challenged with LPS resulted in elevated serum and tissue mRNA levels of cytokines.