Supplementation of direct-fed microbial as an alternative to antibiotic on growth performance, intestinal immune status and epithelial barrier integrity in broiler chicken

Authors: GADDE, UJVALA - US Department Of Agriculture (USDA); LEE, YOUNG - US Department Of Agriculture (USDA); OH, SUNGTAEK - US Department Of Agriculture (USDA); Lillehoj, Hyun

Submitted to: Probiotics and Antimicrobial Proteins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2017
Publication Date: 4/18/2017
Citation: Gadde, U.D., Lee, Y.S., Oh, S., Lillehoj, H.S. 2017. Supplementation of direct-fed microbial as an alternative to antibiotic on growth performance, intestinal immune status and epithelial barrier integrity in broiler chicken. Probiotics and Antimicrobial Proteins. 10.1007/s12602-017-9275-9.

Interpretive Summary: Intestinal health plays an important role in successful poultry production and is a critical factor in improving growth and performance of poultry. Many factors influence gut health, including diet composition, disease status, stress and feed change. Currently, with the increased regulation of antibiotic use, there is a great need for the development of novel alternatives that could positively influence gut health by improving immune responses and barrier function. In this paper, ARS scientists report that certain direct-fed microbials (DFM), often referred to as probiotics, represent a non-antibiotic nutritional approach to modulate gut function and enhance intestinal health in chickens. In this report, the authors showed that dietary Bacillus subtilis-based probiotic supplementation promoted feed efficiency and gut immunity. Furthermore, the broiler chickens fed diets with various levels of B. subtilis exhibited significant improvements in body weights at 14 days of age compared to non-supplemented controls. The intestinal epithelium is an integral component of gut mucosal immunity and serves as a physical barrier against invading pathogens and toxins. In this study, the authors also showed that the oral administration of a probiotic mixture improved intestinal barrier function and optimal gut health. Taken together, this study documented the immunomodulatory activities of B. subtilis strains in the gut. From these results, it can be concluded that supplementation of broiler diets with B. subtilis probiotics influences a diverse array of immune gut barrier functions and provide many beneficial effects for poultry health.

Technical Abstract: The objective of this study was to investigate the effects of supplementation of broiler diets with Bacillus subtilis-based probiotics on growth performance, feed efficiency, intestinal cytokine and tight junction (TJ) protein mRNA expression. Day-old broiler chicks (n = 140) were randomly assigned to one of the five dietary treatments - basal diet (CON), basal diet supplemented with antibiotic (BMD) or probiotics, namely B. subtilis strain 1781 (PB1) or combination of B. subtilis strain 1104+strain 747 (PB2) or B. subtilis strain 1781+strain 747 (PB3). Body weight, feed intake were measured at 14 days of age and FCR was calculated. At 14 days of age, ileal samples were collected and used for intestinal cytokine, TJ proteins, and mucin gene expression analysis by qRT-PCR. The chickens supplemented with antibiotic (BMD) and B. subtilis strain 1781 alone (PB1) showed significantly higher body weight compared to controls at 14 days of age. Supplementation of diets with antibiotic (BMD) or probiotics (PB1, PB2, PB3) significantly improved the feed efficiency as evidenced by decreased FCR compared to controls. No differences were seen in the expression of IL1ß, IL17F, IFN' and MUC2 gene among the different treatment groups. However, elevated expression of IL6 (BMD, PB1, PB2), IL8 (PB2) and TNFSF15 (PB1, PB2, PB3) was seen in the ileum compared to controls. The expression of IL2, IL10 was upregulated in birds of PB2, PB3 groups, IL4 in PB1 group and IL13 was found elevated in all the probiotic-fed groups (PB1, PB2, PB3). The supplementation of probiotics was also shown to significantly increase the expression of TJ proteins JAM2, ZO1 (PB2, PB3) and occludin (PB1, PB2). Taken together, B. subtilis supplementation altered the intestinal immune activities and influenced gut barrier integrity through increased production of TJ proteins.