Effects of feeding Salmonella enterica serovar Typhimurium or serovar Choleraesuis on growth performance and circulating insulin-like growth factor-I, tumor necrosis factor-α, and interleukin-1β in weaned pigs1

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 has been reported to cause systemic disease, a different disease outcome from that of Typhimurium, our working hypothesis was that this serovar would likely engage systemic immune-inflammatory mechanisms, resulting 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. The treatments consisted of a negative control and pigs repeatedly fed 10(8) cfu of Typhimurium or Choleraesuis. On d 0, the pigs were fed Choleraesuis or Typhimurium in dough balls, and the bacteria were refed 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 beginning 2 d before the first bacterial feeding through d 7 using rapid-response digital thermometers. Serum was collected on d 0, 7, and 14 from a single pig/pen for analysis of IGF-I, tumor necrosis factor-alpha , and IL-1beta. There was no change in the rectal temperature of the control or the Typhimurium-challenged pigs (compared with d 0) or when comparing Typhimurium-challenged pigs with control animals. In contrast, pigs fed Choleraesuis had increased rectal temperatures beginning on d 2 and continuing through d 7 (P < 0.05), with the greatest elevation on d 3 (P < 0.001) compared with the control pigs. Average daily gain and ADFI of pigs challenged with Typhimurium did not differ from those of the control animals. Pigs fed Choleraesuis had a 25% reduction in ADG (P < 0.0001) and ADFI (P < 0.002) compared with the control pigs. On d 7, pigs fed Choleraesuis had reduced serum IGF-I compared with control (P < 0.01) or Typhimurium-challenged pigs (P = 0.01). Bacterial feeding did not affect serum tumor necrosis factor-alpha or IL-1beta compared with control pigs at any time throughout the experiment. We conclude that repeated exposure of weaned pigs to Choleraesuis reduced growth performance in the absence of changes in systemic inflammatory cytokines.

Oral inoculation with Salmonella enterica serovar Typhimurium or Choleraesuis promotes divergent responses in the somatotropic growth axis of swine1

“…Clearly, all these measures were affected adversely by repeated oral exposure of pigs to Choleraesuis. In contrast, none of these measures was affected by repeated exposure of pigs to Typhimurium (current report; Fraser et al, 2007). Although we expected Typhimurium to disrupt ADFI, and thereby potentially reduce BW, the oral dose of Typhimurium used in the study was small relative to oral doses reported to provoke enteric disease (Schwartz, 1999) and relative to those we have used previously (Balaji et al, 2000;Turner et al, 2002a,b).…”

“…It is of interest to note that in the companion study conducted with pen mates of pigs from the current study, Choleraesuis challenge was not associated with increased circulating tumor necrosis factor-α or IL-1β (Fraser et al, 2007). However, it is important to note that local production of inflammatory cytokines not measured in the current study may be of greater importance and more reflective of local regulation of skeletal muscle growth than systemic cytokines (reviewed in Gabler and Spurlock, 2008).…”

“…Growth performance data for this experiment were reported previously (Fraser et al, 2007). Clearly, all these measures were affected adversely by repeated oral exposure of pigs to Choleraesuis.…”

“…The current study reports data from additional tissue collections and measurements made from a previously published study (Fraser et al, 2007). Essential details of that study and others specific to the current report are included here for clarity.…”

“…Dough balls were then refed on d 3, 7, and 10, resulting in animals receiving treatment twice weekly through the course of the 14-d study. Details of bacterial culture were described previously (Fraser et al, 2007). All pigs were confirmed to be negative for salmonella organisms by fecal culture before inclusion in the study.…”