AUTHOR=Kan Liugang , Guo Fangshen , Liu Yan , Pham Van Hieu , Guo Yuming , Wang Zhong 

TITLE=Probiotics Bacillus licheniformis Improves Intestinal Health of Subclinical Necrotic Enteritis-Challenged Broilers

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.623739

DOI=10.3389/fmicb.2021.623739

ISSN=1664-302X

ABSTRACT=<p>Necrotic enteritis infection poses a serious threat to poultry production, and there is an urgent need for searching effective antibiotic alternatives to control it with the global ban on in-feed antibiotics. This study was conducted to investigate the effects of dietary <italic>Bacillus licheniformis</italic> replacing enramycin on the growth performance and intestinal health of subclinical necrotic enteritis (SNE)-challenged broilers. In total, 504 1-day-old Arbor Acres male chickens were selected and subsequently assigned into three treatments, including PC (basal diet + SNE challenge), PA (basal diet extra 10 mg/kg enramycin + SNE challenge), and PG (basal diet extra 3.20 × 10<sup>9</sup> and 1.60 × 10<sup>9</sup> CFU <italic>B. licheniformis</italic> per kg diet during 1–21 days and 22–42 days, respectively + SNE challenge). Results showed that <italic>B. licheniformis</italic> significantly decreased the intestinal lesion scores and down-regulated the <italic>Claudin-3</italic> mRNA levels in jejunum of SNE-infected broilers on day 25, but increased the <italic>mucin-2</italic> gene expression in broilers on day 42. In addition, <italic>B. licheniformis</italic> significantly up-regulated the mRNA levels of <italic>TRIF</italic> and <italic>NF-κB</italic> of SNE-challenged broilers compared with the control group on day 25 and <italic>TLR-4</italic>, <italic>TRIF</italic> compared with the control and the antibiotic group on day 42. The mRNA expression of growth factors (<italic>GLP-2</italic> and <italic>TGF-β2</italic>) and HSPs (<italic>HSP60</italic>, <italic>HSP70</italic>, and <italic>HSP90</italic>) were up-regulated in <italic>B. licheniformis</italic> supplementary group on days 25 and 42 compared with group PC. LEfSe analysis showed that the relative abundance of <italic>Lachnospiraceae_UCG_010</italic> was enriched in the PG group; nevertheless, <italic>Clostridiales_vadinBB60</italic> and <italic>Rnminococcaceae_NK4A214</italic> were in PA. PICRUSt analysis found that the metabolism of cofactors and vitamins, amino acid metabolism, and carbohydrate metabolism pathways were enriched, whereas energy metabolism, membrane transport, cell motility, and lipid metabolism were suppressed in <italic>B. licheniformis</italic>-supplemented groups as compared with the PC control. In conclusion, dietary supplementation of <italic>B. licheniformis</italic> alleviated the intestinal damage caused by SNE challenge that coincided with modulating intestinal microflora structure and barrier function as well as regulating intestinal mucosal immune responses.</p>