ALTERATIONS IN THE RESPONSE OF PIGS TO SALMONELLA TYPHIMURIUM WHEN PROVIDED ENTEROBACTER CLOACAE

Abstract Text:

Weanling pigs are at risk of succumbing to illness due to an immature immune system and insufficient supply of available energy at the time of weaning. Recent evidence has suggested that providing pigs with Enterobacter cloacae can increase the concentration of circulating triglycerides (TAGs) and thus available energy. In order to determine if this increase in TAGs improved the response of pigs to an infection, 36 weaned pigs 30 d of age (6.7 ± 0.1 kg BW) were individually housed and randomly assigned to three treatment groups: 1) Enterobacter cloacae (JD6301; 1x10¹⁰ CFU); 2) an alternate form of this bacterium (JD8715; 1x10¹⁰ CFU) that secretes TAGs into the surrounding environment; or a control of PBS. For each treatment, bacteria were supplemented to the water daily using a medicator water system (~1x10⁶ CFU/mL). Pigs were provided water supplemented with E. cloacae for 5 d prior to and 3 d afterwards in relation to being challenged with lipopolysaccharide (LPS) from Escherichia coli (25 ug/kg BW, time 0 h) and Salmonella typhimurium (1x10⁹ CFU, time 6 h). Serum samples were collected every 6 h for a period of 72 h and analyzed for non-esterified fatty acids (NEFAs), TAGs, and whole blood cell counts. At 24 h, 48 h, and 72 h post-challenge, gastrointestinal contents were collected and analyzed for the presence of E. cloacae and S. typhimurium. Circulating TAGs increased (P = 0.05) in pigs provided JD6301 in comparison to PBS controls within 5 d of supplementation, but did not increase (P = 0.33) in pigs provided JD8715. Within 18 h post-challenge with LPS (and 12 h post-challenge with S. typhimurium), an increase in NEFAs (P < 0.05) and TAGs (P < 0.04) was observed in pigs provided PBS in comparison to pigs provided either form of E. cloacae. Pigs provided JD6301 had a reduction (P = 0.05) in S. typhimurium populations between 24 to 72 h post-challenge. However, S. typhimurium populations in pigs provided either JD8715 or PBS did not decrease (P = 0.18) during this time period. Pigs provided JD8715 did have an increase (P = 0.05) in neutrophil concentrations within 6 h post-exposure to the endoxotin. These data suggest that the oleaginous bacteria JD6301 may improve clearance of S. typhimurium from the gastrointestinal tract. Further research is needed to determine whether this decrease is due to an improved immune response or competitive inhibition.

Keywords: pigs, triglycerides, probiotics