Effects of Dietary Supplementation With Bacillus subtilis, as an Alternative to Antibiotics, on Growth Performance, Serum Immunity, and Intestinal Health in Broiler Chickens
- 2021-11-29
- Frontiers in Nutrition 8
- Kai Qiu
- Cheng-liang Li
- Jing Wang
- G. Qi
- Jun Gao
- Haijun Zhang
- Shu-geng Wu
- PubMed: 34917643
- DOI: 10.3389/fnut.2021.786878
Abstract
Bacillus subtilis (B. subtilis) as in-feed probiotics is a potential alternative for antibiotic growth promoters (AGP) in the poultry industry. The current study investigated the effects of B. subtilis on the performance, immunity, gut microbiota, and intestinal barrier function of broiler chickens. A 42-day feeding trial was conducted with a total of 600 1-day-old Arbor Acres broilers with similar initial body weight, which was randomly divided into one of five dietary treatments: the basal diet (Ctrl), Ctrl + virginiamycin (AGP), Ctrl + B. subtilis A (BSA), Ctrl + B. subtilis B (BSB), and Ctrl + B. subtilis A + B (1:1, BSAB). The results showed significantly increased average daily gain in a step-wise manner from the control, B. subtilis, and to the AGP groups. The mortality rate of the B. subtilis group was significantly lower than the AGP group. The concentrations of serum immunoglobulin (Ig) G (IgG), IgA, and IgM in the B. subtilis and AGP groups were higher than the control group, and the B. subtilis groups had the highest content of serum lysozyme and relative weight of thymus. Dietary B. subtilis increased the relative length of ileum and the relative weight of jejunum compared with the AGP group. The villus height (V), crypt depth (C), V/C, and intestinal wall thickness of the jejunum in the B. subtilis and AGP groups were increased relative to the control group. Dietary B. subtilis increased the messenger RNA (mRNA) expression of ZO-1, Occludin, and Claudin-1, the same as AGP. The contents of lactic acid, succinic acid, and butyric acid in the ileum and cecum were increased by dietary B. subtilis. Dietary B. subtilis significantly increased the lactobacillus and bifidobacteria in the ileum and cecum and decreased the coliforms and Clostridium perfringens in the cecum. The improved performance and decreased mortality rate observed in the feeding trial could be accrued to the positive effects of B. subtilis on the immune response capacity, gut health, and gut microflora balance, and the combination of two strains showed additional benefits on the intestinal morphology and tight junction protein expressions. Therefore, it can be concluded that dietary B. subtilis A and B could be used as alternatives to synthetic antibiotics in the promotion of gut health and productivity index in broiler production.
Keywords: Bacillus subtilis; broiler chickens; gut microbiota; immunity; probiotic.
Research Insights
| Supplement | Health Outcome | Effect Type | Effect Size |
|---|---|---|---|
| Bacillus Subtilis | Improved Average Daily Gain | Beneficial | Moderate |
| Bacillus Subtilis | Improved Gut Microflora | Beneficial | Moderate |
| Bacillus Subtilis | Improved Intestinal Morphology | Beneficial | Moderate |
| Bacillus Subtilis | Improved Tight Junction Protein Expression | Beneficial | Moderate |
| Bacillus Subtilis | Increased Short-Chain Fatty Acid Levels | Beneficial | Moderate |
| Bacillus Subtilis | Reduced Mortality Rate | Beneficial | Large |
| Bacillus subtilis AB22 | Enhanced Beneficial Gut Microbiota | Beneficial | Moderate |
| Bacillus subtilis AB22 | Improved Average Daily Gain | Beneficial | Moderate |
| Bacillus subtilis AB22 | Improved Intestinal Morphology | Beneficial | Moderate |
| Bacillus subtilis AB22 | Improved Tight Junction Protein Expression | Beneficial | Moderate |
| Bacillus subtilis AB22 | Increased Serum Immunoglobulins | Beneficial | Moderate |
| Bacillus subtilis AB22 | Increased Serum Lysozyme Levels | Beneficial | Moderate |
| Bacillus subtilis AB22 | Increased Thymus Weight | Beneficial | Small |
| Bacillus subtilis AB22 | Reduced Harmful Microorganisms | Beneficial | Moderate |
| Bacillus subtilis AB22 | Reduced Mortality Rate | Beneficial | Large |
| Bacillus subtilis DE11 | Improved Average Daily Gain | Beneficial | Moderate |
| Bacillus subtilis DE11 | Improved Gut Microbiota Balance | Beneficial | Large |
| Bacillus subtilis DE11 | Improved Immune Response | Beneficial | Large |
| Bacillus subtilis DE11 | Improved Intestinal Function | Beneficial | Large |
| Bacillus subtilis DE11 | Improved Tight Junction Protein Expression | Beneficial | Moderate |
| Bacillus subtilis DE11 | Increased Short-Chain Fatty Acid Production | Beneficial | Moderate |
| Bacillus subtilis DE11 | Reduced Colitis-Related Mortality | Beneficial | Moderate |
| Bacillus subtilis DE111 | Elevated Serum Immunoglobulin Levels | Beneficial | Moderate |
| Bacillus subtilis DE111 | Enhanced Beneficial Gut Microbiota | Beneficial | Moderate |
| Bacillus subtilis DE111 | Improved Average Daily Gain | Beneficial | Moderate |
| Bacillus subtilis DE111 | Improved Intestinal Morphology | Beneficial | Moderate |
| Bacillus subtilis DE111 | Improved Tight Junction Protein Expression | Beneficial | Moderate |
| Bacillus subtilis DE111 | Increased Serum Lysozyme Levels | Beneficial | Moderate |
| Bacillus subtilis DE111 | Increased Short Chain Fatty Acids | Beneficial | Small |
| Bacillus subtilis DE111 | Reduced Colitis-Related Mortality | Beneficial | Moderate |
| Bacillus subtilis HU58 | Elevated Serum Immunoglobulin Levels | Beneficial | Moderate |
| Bacillus subtilis HU58 | Improved Average Daily Gain | Beneficial | Moderate |
| Bacillus subtilis HU58 | Improved Gut Microbiota Balance | Beneficial | Large |
| Bacillus subtilis HU58 | Improved Intestinal Barrier Function | Beneficial | Moderate |
| Bacillus subtilis HU58 | Improved Intestinal Morphology | Beneficial | Moderate |
| Bacillus subtilis HU58 | Increased Short-Chain Fatty Acid Levels | Beneficial | Moderate |
| Bacillus subtilis HU58 | Reduced Colitis-Related Mortality | Beneficial | Moderate |
| Bacillus subtilis MB40 | Improved Average Daily Gain | Beneficial | Moderate |
| Bacillus subtilis MB40 | Improved Intestinal Morphology | Beneficial | Moderate |
| Bacillus subtilis MB40 | Increased Beneficial Gut Microbiota | Beneficial | Large |
| Bacillus subtilis MB40 | Increased Serum Immunoglobulin Levels | Beneficial | Large |
| Bacillus subtilis MB40 | Increased Short-Chain Fatty Acid Levels | Beneficial | Moderate |
| Bacillus subtilis MB40 | Increased Tight Junction Protein Gene Expression | Beneficial | Large |
| Bacillus subtilis MB40 | Reduced Harmful Gut Bacteria | Beneficial | Moderate |
| Bacillus subtilis MB40 | Reduced Mortality Rate | Beneficial | Large |
| Bacillus subtilis SNZ-1972 | Balanced Gut Microbiota | Beneficial | Large |
| Bacillus subtilis SNZ-1972 | Improved Growth Performance | Beneficial | Large |
| Bacillus subtilis SNZ-1972 | Improved Intestinal Barrier Function | Beneficial | Moderate |
| Bacillus subtilis SNZ-1972 | Improved Intestinal Morphology | Beneficial | Moderate |
| Bacillus subtilis SNZ-1972 | Reduced Colitis-Related Mortality | Beneficial | Moderate |