Dose-dependent effects of supplementing a two-strain Bacillus subtilis probiotic on growth performance, blood parameters, fecal metabolites, and microbiome in nursery pigs

Authors: SMITH, ALEXANDRA - Arm & Hammer Animal And Food Production; HERNANDEZ, SAMANTHA - Arm & Hammer Animal And Food Production; WENNER, SETH - Arm & Hammer Animal And Food Production; FREGULIA, PRISCILA - Oak Ridge Institute For Science And Education (ORISE); LARSEN, ANNA - Oak Ridge Institute For Science And Education (ORISE); Li, Wenli; JANG, YANG - University Of Georgia; DUDDECK, KARYN - University Of Wisconsin-River Falls, Department Of Plant And Earth Science; PETERSEN, TIFFANY - University Of Wisconsin-River Falls, Department Of Plant And Earth Science; ADKINS, HALEY - University Of Wisconsin-River Falls, Department Of Plant And Earth Science; YAO, DAN - University Of Minnesota; CHI, CHEN - University Of Minnesota

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2023
Publication Date: 12/28/2023
Citation: Smith, A., Hernandez, S., Wenner, S., Fregulia, P., Larsen, A., Li, W., Jang, Y., Duddeck, K., Petersen, T., Adkins, H.J., Yao, D., Chi, C. 2023. Dose-dependent effects of supplementing a two-strain Bacillus subtilis probiotic on growth performance, blood parameters, fecal metabolites, and microbiome in nursery pigs. Animals. https://doi.org/10.3390/ani14010109.
DOI: https://doi.org/10.3390/ani14010109

Interpretive Summary: Weaning is one of the most stressful periods in the pig’s life, involving sudden changes in diet, and in its social and living environment. A common issue with newly weaned pigs is postweaning diarrhea primarily caused by Escherichia coli. Probiotics have been widely used in swine diets to improve intestinal health of postweaning piglets by reducing pathogenic bacteria, enhancing beneficial bacterial proliferation, and stimulating the immune system. Bacillus subtilis has been shown to reduce the incidence and severity of diarrhea in nursery pigs, though its effect in improving growth performance is largely unexplored. By providing dietary supplementation at 1.875×10^5 CFU/g diet to nursery diets with two Bacillus subtilis strains selected to reduce effects of pathogenic E. coli, we observed that this probiotic diet supplementation improved growth rate in the early postweaning period and altered fecal microbial community composition and the associated short chain fatty acid concentrations associated with it. Increasing the B. subtilis supplement ten-fold (1.875×10^6 CFU/g diet) did not lead to improved performance parameters, suggesting there might be a concentration threshold to fully harness the beneficial effects of probiotic dosing. However, the exact upper threshold of effective B. subtilis supplement needs further investigation.

Technical Abstract: This experiment was conducted to evaluate the effects of dietary supplementation level of a two-strain Bacillus subtilis probiotic on growth performance, blood parameters, fecal metabolites, and microbiome in nursery pigs as certain strains of B. subtilis have been shown to reduce the incidence and severity of diarrhea and therefore improve growth performance of nursery pigs. A total of 54 newly weaned piglets were allotted to 3 treatments in 3 replicates with 6 pigs per pen for a 28-d feeding trial. Treatments were: 1) Control: no probiotics supplementation, 2) Pro1x: Bacillus subtilis supplementation level at 1.875×10^5 CFU/g, and 3) Pro10x: B. subtilis supplementation at 1.875×10^6 CFU/g diet. The probiotic product consisted of a blend of two strains selected to inhibit pathogenic F18 Escherichia coli strains. Corn-soybean meal-based diets were used for d 0-14 (Phase 1) and d 14-28 (Phase 2) postweaning. Body weight, blood glucose and creatinine, fecal short chain fatty acid (SCFA) and bile acid concentrations were measured at d 14 and 28 postweaning. Body weight at d 14 postweaning (P=0.06) and average daily gain for d 0 to 14 postweaning (P<0.05) were greater in the Pro1x treatment than the control and Pro10x treatments, although there was no significant difference in growth performance at d 28 postweaning. Blood glucose levels were greater in both probiotic treatments than the control treatment at d 14 postweaning (P<0.05). For SCFA concentrations, butyrate was greater in the Pro1x treatment than the control and Pro10x treatments (P<0.05). The acetate, propionate, and total SCFA concentrations were greater in the Pro1x treatment than the Pro10x treatment with the intermediate value in the control treatment (P<0.05). There were no significant differences in fecal bile acid concentrations and blood creatinine levels at both d 14 and 28 postweaning. In conclusion, dietary supplementation of Pro1x increased fecal SCFA concentrations, and altered fecal bile acid and microbial community composition at the lower tested dose. A higher dose of the probiotic, Pro10x, did not improve the measured performance parameters over that of the control piglets.