Effects of Feeding Salmonella enterica serovar Typhimurium or serovar Choleraesuis to Weaned Pigs on Growth Performance and Circulating Insulin-like Growth Factor-I, Tumor Necrosis Factor Alpha, and Interleukin-1 Beta

¹ Department of Animal Sciences and Industry, Weber Hall, Kansas State University, Manhattan, KS 66506-0201. T. E. Burkey's current address: 206f Animal Sciences, University of Nebraska, P.O. Box 830908, Lincoln, NE 68583-0908
² Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506-5601

^* To whom correspondence should be addressed. E-mail: eminton{at}ksu.edu.

	Abstract

The most common Salmonella serovars causing clinical disease in pigs are Salmonella enterica serovars Typhimurium (Typhimurium) and Choleraesuis. Given that the swine host-adapted serovar Choleraesuis was reported to cause systemic disease, a very different disease outcome than that of Typhimurium, our working hypothesis was that this serovar would likely engage systemic immune-inflammatory mechanisms that would result in elevated systemic cytokine secretion. Forty-eight weaned pigs were blocked by BW and sex, and randomly allotted to 1 of 3 treatments in a 14-d study. Each treatment had 8 replicates (pens) with 2 pigs/pen. Treatments consisted of a negative control and pigs repeatedly fed either 10⁸ CFU Typhimurium or Choleraesuis. On d 0, pigs were fed Choleraesuis or Typhimurium in dough balls, and bacteria were re-fed twice weekly throughout the experiment. Control pigs received dough balls without bacteria. All pigs were housed in temperature-controlled rooms under constant lighting and were fed a standard corn-soybean meal-based nursery diet. Pig BW and feed disappearance were used to determine ADG, ADFI, and G:F. Rectal temperatures were obtained daily from 1 pig/pen starting 2 d before the first bacterial feeding through d 7 using rapid-response digital thermometers. Serum was collected from a single pig/pen for analysis of IGF-I, tumor necrosis factor alpha (TNF) and interleukin-1 beta (IL-1) on d 0, 7, and 14. There was no change in the rectal temperature of both the control and the Typhimurium challenged pigs (compared with day 0) or when comparing Typhimurium challenged pigs to controls. In contrast, pigs fed Choleraesuis had increased rectal temperature beginning on d 2 and continuing though d 7 (P < 0.05) with the greatest elevation on d 3 (P < 0.001) compared with controls. Average daily gain and ADFI of pigs challenged with Typhimurium did not differ from those of the control pigs. Pigs fed Choleraesuis had about a 25% reduction in ADG (P < 0.0001) and ADFI (P < 0.002) compared with control pigs. On d 7, pigs fed Choleraesuis had reduced IGF-I compared with both control (P < 0.01) and Typhimurium pigs (P = 0.01). Bacterial feeding did not affect serum TNF and IL-1 compared with control pigs at any time throughout the experiment. We conclude that repeated exposure of weaned pigs to Choleraesuis eroded growth performance in the absence of changes in systemic inflammatory cytokines.

Key Words: Insulin-like growth factor-I, Interleukin-1, Salmonella enterica, Swine, Tumor necrosis factor

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