Effects of dietary live yeast supplementation on growth and immunological parameters of weaned piglets challenged with Escherichia coli K88

Abstract Text: This study aimed to investigate the effects of dietary live yeast (Saccharomyces cerevisiae , Phileo Lesaffre Animal Care, France) supplementation on growth performance and immunological parameters of piglets challenged with enterotoxigenic Escherichia coli K88. A total of 180 weaned piglets (6.39±0.05 kg) were randomly allocated into 5 treatments with 6 pens and 6 piglets (3 barrows and 3 gilts) per pen, receiving the control (CON) diet, diets supplemented with antibiotics plus ZnO (ABT-ZnO:2250 mg/kg of ZnO, 20 mg/kg Colistin and 75 mg/kg Aureomycin), live yeast at 1 (LY1), 2.5 (LY2.5) or 5 g/kg (LY5) for a period of 2 weeks. On day 8, six piglets from CON group received sterilized Luria Broth as control (n=6), while another 30 piglets from CON (n=6), antibiotic plus ZnO (n=6), LY1(n=6), LY2.5 (n=6) and LY5 (n=6) groups, were orally challenged with Luria Broth containing 1x10¹¹ cfu of E.Coli K88. Body weights and pen feed disappearance were recorded weekly to determine ADG, ADFI and F:G. On d 10, blood, ileum and mesenteric lymph node (MLN) tissue samples were collected at necropsy and analyzed for immunological parameters. Data were analyzed by SPSS software using the GLM procedure. Pigs fed ABT-ZnO diet had higher (P<0.05) ADG and ADFI than pigs fed CON, LY1 and LY5 diets during the first week, while ADFI and F:G were similar between pigs fed ABT-ZnO and LY2.5 diets. Moreover, the ADG of pigs fed LY1 diet was similar to pigs fed ABT-ZnO diet during the second week. Compared with the pigs fed ABT-ZnO diet and non-challenged pigs, pigs fed LY2.5 and LY5 diets had higher (P<0.05) plasma concentration of immunoglobulin G. Relative to the non-challenged pigs, moreover, the plasma concentration of Pig Major Acute Phase Protein (PMAPP) was increased (P<0.05) in the challenged pigs fed CON diet, but PMAPP had not been markedly affected in the pigs previously fed ABT-ZnO and LY5 diets. Relative to the non-challenged pigs, E.Coli K88 challenge up-regulated (P<0.05) the mRNA abundances of toll-like receptor 4 (TLR-4), toll-like receptor 9 (TLR-9), myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF-6) and interleukin-6 (IL-6) in ileum, however, those genes was down-regulated by feeding LY5 diet.In conclusion, pigs fed live yeast diet had similar ADFI and F:G as pigs fed ABT-ZnO diet during the first week, the higher inclusion of live yeast could improve immunological parameters of piglets challenged with E.coli K88.

Keywords:  live yeast, immunity, intestine