Cytokine mRNA Expression in the Small Intestine of Weanling Pigs Fed Diets Supplemented with Specialized Protein or Peptide Sources

Cytokines play a central role in the mucosal immune response and are involved in regulation of nutrient absorption, metabolism and animal growth This study investigated the effect of diet manipulation with specialized protein or peptide sources on expression of cytokine (IL-1, IL-6, IL-10, and TNF-alpha) mRNA abundance in different intestinal regions and at different ages post-weaning in piglets. A total of 48 (17 days of age, 6.16 +/- 0.34 kg BW) weanling pigs were fed either a corn-soy/whey protein basal diet, the basal diet supplemented with spray-dried plasma protein (SDPP), or the basal diet supplemented with Peptiva (R), a hydrolyzed marine plant protein. A fourth treatment group was fed the SDPP diet, but the feed intake level was limited (SDPP-LF). Pigs were killed at 3 and 10 d, and intestinal cytokine mRNA was measured by real-time PCR using the relative quantification method. The SDPP-LF group exhibited an increased TNF-alpha mRNA abundance compared with the ad libitum SDPP group (p<0.05). The TNF-alpha and IL-10 mRNA abundance increased from the proximal to distal part of the intestine, and the mRNA abundance was greater (p<0.01) in the distal intestine as compared with the proximal and middle intestine. The cytokines IL-1-beta, IL-10 and TNF-alpha mRNA abundance also increased from d3 to d10 postweaning (p<0.01). In summary, restricted feeding increased the TNF-alpha mRNA abundance in the small intestine, however neither SDPP nor peptide supplementation affected cytokine mRNA expression. Abundance of mRNA for most cytokines examined in this study increased with age post-weaning, suggesting that during 10 d after weaning the mucosal immune system is still under development.