Effects of mixed organic acids and medium chain fatty acids as antibiotic alternatives on the performance, serum immunity, and intestinal health of weaned piglets orally challenged with Escherichia coli K88

摘要

This study was performed to evaluate the effects of combinations of organic acids and medium chain fatty acids (OAMF) as antibiotic alternatives on the performance, serum immunity, and intestinal functions of weaned piglets orally challenged with Escherichia coll. K88 (E. coli K88). A total of 150 28-day-old piglets (8.75 +/- 0.14 kg) were allocated to five treatments, with five replicates (six piglets) per treatment. The treatments were NC (basal diet); PC (basal diet + E. coli); AGP (basal diet + E. coli + 0.04 g/kg zinc bacitracin, 0.03 g/kg chlortetracycline, and 0.05 g/kg kitasamycin); OAMF1 (basal diet + E. coli + 2 g/kg OAMF1 overall period); and OAMF2 (basal diet + E.coli + 8 g/kg OAMF2 during days 1 - 14, and 6 g/kg during days 15 - 28). On day 15, piglets in the PC, AGP, OAMF1, and OAMF2 groups were orally challenged with 20 mL E. coli K88 [10 8 colony-forming units (CFU)/mL]. Compared with those in the NC group, piglets in the AGP and OAMF1 groups had higher body weights (BW) on day 14 and greater average daily gain (ADG) between days 1 and 14 (P < 0.05). E. coli K88 challenge significantly increased the fecal scores in the PC group (P < 0.05), and the fecal scores in the OAMF1 and OAMF2 groups were lower than that in the PC group (P < 0.05), and higher than that in the AGP group (P < 0.05). Supplementation with OAMF decreased total leukocytes and the percentage of neutrophils (P < 0.05), increased the percentage of lymphocytes (P < 0.05), and increased serum immunoglobulin M (IgM) levels on day 14 and immunoglobulin G (IgG) levels on days 14 and 21 (P < 0.05). Compared with the NC group, the OAMF2 group showed a significantly higher serum interleukin 1 beta (IL-1 beta) level on day 21 (P < 0.05). The intestinal villus height and villus height/ crypt depth were increased by OAMF supplementation (P < 0.05). E. coli K88 challenge significantly increased the relative abundance of Firmicutes (P < 0.05) and decreased that of Proteobacteria (P < 0.05). Supplementation with OAMF1 decreased the relative abundance of Fusobacteria (P < 0.05) and tended to increase microbiota diversity (P = 0.078). In summary, dietary supplementation with OAMF had positive effects in reducing fecal scores, enhancing immune function, improving intestinal morphology, and stabilizing the ileal bacterial community structure. Thus, OAMF may be used as potential alternatives to AGPs in weanling piglets.