We investigated the effects of different Bacillus subtilis QST713 doses and a B. subtilis QST713 and β-mannanase mix on growth performance, intestinal barrier function, and gut microbiota in weaned piglets. In total, 320 healthy piglets were randomly assigned to four groups: 1) control group (basal diet), 2) BS100 group (basal diet plus 100 mg/kg B. subtilis QST713), 3) BS200 group (basal diet plus 200 mg/kg B. subtilis QST713), and 4) a BS100XT group (basal diet plus 100 mg/kg B. subtilis QST713 and 150 mg/kg β-mannanase). The study duration was 42 d. We showed that feed intake in weaned piglets on days 1 to 21 was increased in group BS100 (P < 0.05), and that the feed conversion ratio in group BS100XT animals decreased throughout the study (P < 0.05). In terms of microbial counts, the BS100XT group showed reduced Escherichia coli and Clostridium perfringens numbers on day 21 (P < 0.05). Moreover, no significant α-diversity differences were observed across all groups during the study (P > 0.05). However, principal coordinates analysis indicated clear separations in bacterial community structures across groups (analysis of similarities: P < 0.05) on days 21 and 42. Additionally, E-cadherin, occludin, and zonula occludens-1 (ZO-1) expression in piglet feces increased (P < 0.05) by adding B. subtilis QST713 and β-mannanase to diets. Notably, this addition decreased short-chain fatty acid concentrations. In conclusion, B. subtilis QST713 addition or combined B. subtilis QST713 plus β-mannanase effectively improved growth performance, intestinal barrier function, and microbial balance in weaned piglets.
Keywords: Bacillus subtilis; combined Bacillus subtilis and β-mannanase; gut microbiota; weaned piglets; β-mannanase.
The use of antibiotics in pig farming raises serious concerns in terms of antibiotic resistance. Consequently, alternative approaches such as probiotics, including Bacillus subtilis, and enzymes such as β-mannanase, have been proposed to improve pig health and performance. In particular, B. subtilis improves gut microbiota and reduces the prevalence of harmful bacteria such as Escherichia coli and Clostridium perfringens. Similarly, β-mannanase enhances feed digestibility and improves nutrient use in pigs. Thus, combined B. subtilis and β-mannanase may provide synergistic effects toward pig performance and gut health. In this study, we showed that adding B. subtilis to a weaned piglet diet improved feed intake, while a B. subtilis and β-mannanase mix reduced feed conversion ratios in weaned piglets.
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