Effects of benzoic acid, Bacillus coagulans and oregano oil combined supplementation on growth performance, immune status and intestinal barrier integrity of weaned piglets

This experiment was conducted to investigate the effects of benzoic acid, Bacillus coagulans and oregano oil combined supplementation on growth performance, immune status and intestinal barrier integrity of piglets. In a 26-d experiment, 25 piglets were randomly assigned to 5 treatments: 1) a basal diet, negative control (NC), 2) NC added with antibiotics, positive control (PC); 3) NC added with benzoic acid at 3,000 g/t and Bacillus coagulans at 400 g/t (AB); 4) NC added with benzoic acid at 3,000 g/t and oregano oil at 400 g/t (AO); 5) NC added with 3,000 g/t benzoic acid and Bacillus coagulans at 400 g/t and oregano oil at 400 g/t (ABO). On d 27, all piglets were euthanized to obtain jejunal mucosa to measure immune status and intestinal barrier integrity. Results showed that pigs fed AB diet increased the final body weight and average daily body weight gain and decreased the ratio of feed to gain compared with NC group (P < 0.05). Compared with NC group, AB, AO and ABO decreased serum tumor necrosis factor-α concentration and ABO decreased interleukin-1β concentration in serum and jejunal mucosa (P < 0.05). Compared with NC group, AB up-regulated mRNA expressions of sodium-glucose cotransporte1, claudin-1, occludin and mucin2 in jejunal mucosa and the populations of Bifidobacterium and Bacillus in cecal digesta (P < 0.05). Compared with NC group, ABO increased jejunal mucosal occludin mRNA abundance and Bifidobacterium population in cecal digesta, and decreased Escherichia coli population in cecal digesta (P < 0.05). Furthermore, AB and ABO increased Bacillus population in cecal digesta compared with PC group (P < 0.05). These results indicated that dietary AB supplementation could improve growth performance and intestinal barrier integrity of piglets when fed antibiotic-free diets, which was possibly associated with the improvement of immune status and intestinal microflora. Dietary ABO supplementation is also beneficial to improve immune status and intestinal barrier integrity and microflora of piglets.