Protective Effects of Benzoic Acid,BacillusCoagulans, and Oregano Oil on Intestinal Injury Caused by EnterotoxigenicEscherichia coliin Weaned Piglets

Abstract

The use of antibiotics as growth promoters in feed has been fully or partially banned in several countries. The objective of this study was to investigate the effects of benzoic acid (A),bacilluscoagulans (B) and oregano oil (O) combined supplementation on growth performance and intestinal barrier in piglets challenged with enterotoxigenicEscherichia coli(ETEC). Thirty piglets were randomly assigned to 6 treatments: (1) nonchallenged control (CON); (2) ETEC-challenged control (ETEC); (3) antibiotics + ETEC (AT); (4) A + B + ETEC (AB); (5) A + O + ETEC (AO); (6) A + B + O + ETEC (ABO). On day 22, piglets were orally challenged with ETEC or saline. The trial lasted 26 days. Dietary AO and ABO inhibited the reduction of growth performance and the elevation of diarrhoea incidence in piglets induced by ETEC (P<0.05). AB, AO, and ABO prevented the elevation of serum TNF-αand LPS concentrations in piglets induced by ETEC (P<0.05). ABO alleviated the elevation of TNF-αand IL-1βconcentrations and the reduction of sIgA level in jejunal mucosa induced by ETEC (P<0.05). Furthermore, ABO upregulated mRNA expressions of Claudin-1 and Mucin2 (P<0.05), downregulated mRNA abundances of TLR4 and NOD2 signaling pathways related genes in jejunal mucosa (P<0.05), and improved the microbiota in jejunal and cecal digesta (P<0.05) compared with ETEC group. These results indicated that benzoic acid,bacilluscoagulans, and oregano oil combined supplementation could improve growth performance and alleviate diarrhoea of piglets challenged with ETEC via improving intestinal mucosal barrier integrity, which was possibly associated with the improvement of intestinal microbiota and immune status. The combination of 3000 g/t benzoic acid + 400 g/tbacilluscoagulans + 400 g/t oregano oil showed better effects than other treatments in improving growth performance and intestinal health of piglets, which could be used as a viable substitute for antibiotic.