Authors : Chad Thomas Collier, Jeffery A. Carroll, Todd R. Callaway and John D. Arthington
Abstract: The effects of Citrus Pulp (CTP) on the immune and cortisol responses to E. coli F18 inoculation and subsequent E. coli recovery were evaluated in newly weaned pigs (23.3±1.8 days of age). Barrows were assigned to 1 of 2 treatment groups with (CTP; n = 15) and without (Control; n = 15) the in-feed inclusion of CTP (10% rate as fed) for 13 days. On day 13, all pigs were orally dosed with Novobiocin (Nov) and Nalidixic Acid (Nal) resistant E. coli F18 (10 mL 7x108 CFU) at 0 h. Serial blood samples were collected via an indwelling jugular catheter inserted on day 12 at hourly intervals from 0-8 h and then at 12, 24, 36 and 48 h. Differential blood cell populations were enumerated hourly from 0-8 h and at 12, 24, 36 and 48 h. Serum cortisol, interleukin-1 beta (IL-1β), IL-6, Tumor Necrosis Factor-alpha (TNF-α) and interferon-gamma (IFN-γ) concentrations were determined via porcine-specific ELISAs at all time points. After 48 h, all pigs were euthanized and samples collected from ileal, cecal and rectal contents for selective E. coli F18 standard plate counts on Nov and Nal-treated media. White blood cells, lymphocytes, neutrophils and macrophages were decreased (p<0.05) from baseline equally in both treatments by 48 h. A more rapid cortisol suppression (p<0.05) was observed in CTP-treated piglets after inoculation with a subsequent return to baseline in both treatments. The production of IL-1β, IL-6, TNF-α and IFN-γ were unaffected by treatment or inoculation. However, the inclusion of CTP suppressed (p<0.05) ileal and cecal E. coli F18 recovery compared to controls and completely eliminated rectal recovery of the pathogen. These results demonstrate that the potentially therapeutic effects of CTP are the result of direct microbial modulation independent of an immune response. Therefore, supplementation of CTP could potentially be used to enhance growth in weaned pigs by suppressing chronic and acute pathogenic challenges; consequently preventing the diversion of energy towards maintaining innate and adaptive immune responses and liberating it for growth related processes.
Chad Thomas Collier, Jeffery A. Carroll, Todd R. Callaway and John D. Arthington, 2010. Oral Administration of Citrus Pulp Reduces Gastrointestinal Recovery of Orally Dosed Escherichia coli F18 in Weaned Pigs. Journal of Animal and Veterinary Advances, 9: 2140-2145.