PSIV-B-37 Late-Breaking: Dietary organic and medium chain fatty acids as antibiotic substitutes improve growth performance, immune function, intestinal morphology and microbiota of weaned piglets orally challenged with Escherichia coli K88

Abstract This study was conducted to determine the effects of organic and medium chain fatty acids (OMCFA) as antibiotic substitutes on growth performance, immune function, intestinal morphology, and ileum microbiota of weaned piglets challenged with Escherichia coli K88. Over 28 days, 150 weaned piglets (28-day old, 8.80 ± 0.19 kg) were allocated to five treatments (with five replicates of six piglets each): negative basal diet (NBD), positive basal diet (PBD), antibiotic growth promoters diet (AGPD, BD+0.04 g/kg zinc bacitracin, 0.03 g/kg chlortetracycline, and 0.05 g/kg kitasamycin), OMCFA 1 diet (BD+0.2% OMCFA, OMCFA is a synergistic blend of a phenolic compound, slow release C12, target release butyrates, formic, acetic, lactic, propionic, citric, sorbic acid), and OMCFA 2 diet (Day 1 to 14: BD+0.8% OMCFA, Day 15 to 28: BD+0.6% OMCFA). On the 15th day, piglets in the PBD, AGPD, OMCFA 1, and OMCFA 2 treatment groups were orally challenged with 20 mL Escherichia coli K88 (108 CFU/mL). Body weight on day 14 and average daily gain from 1st to 14th day of the subjects in the AGPD and OMCFA 1 groups were higher than those in the NBD and PBD groups (P < 0.05). Diarrhea rate after challenge was lower in the AGPD group than PBD one, and there was no significant difference between the AGPD and OMCFA 1 group. OMCFA decreased total leukocytes and the percentage of neutrophils (P < 0.05), increased the percentage of lymphocytes (P < 0.05), on day 14, and increased villus height and villus height/crypt depth ratio in the duodenum, jejunum, and ileum, compared with PBD group. 16S rDNA sequencing showed that OMCFA might stabilize the ileum microbiota caused by E. coli K88 challenge. These results indicated that OMCFA could be used as potential alternatives to AGPs in weaned piglets.