Beneficial effects of dietary supplementation of Bacillus strains on growth performance and gut health in chicken with mixed coccidiosis infection

Authors: CHAUDHARI, ATUL - US Department Of Agriculture (USDA); LEE, YOUNGSUB - US Department Of Agriculture (USDA); Lillehoj, Hyun

Submitted to: Probiotics and Antimicrobial Proteins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2019
Publication Date: 1/1/2020
Citation: Chaudhari, A., Lee, Y., Lillehoj, H.S. 2020. Beneficial effects of dietary supplementation of Bacillus strains on growth performance and gut health in chicken with mixed coccidiosis infection. Probiotics and Antimicrobial Proteins. https://doi.org/10.1016/j.psj.2019.10.023.
DOI: https://doi.org/10.1016/j.psj.2019.10.023

Interpretive Summary: Intestinal health plays an important role in optimizing growth performance of poultry. Among the several predisposing factors that influence the intestinal health, disease status and stress are important. Antibiotic growth promoters (AGPs) have been added to animal feed to decrease infections and to promote their growth rate in commercial chickens. However, due to the emergence of antibiotic-resistant bacteria from chickens fed with sub-therapeutic doses of antibiotics, animal agriculture industry worldwide is forced to seek effective alternatives to antibiotics strategies. In chickens, coccidiosis which is caused by several different species of Eimeria parasite poses a serious economic threats to poultry industry globally. Recent studies have found that non-drug alternatives that can improve gut health by enhancing host immune responses and gut barrier function could be an effective strategy in the control of coccidiosis. In this report, ARS scientists and the collaborators found that direct-fed microbials (DFM) can provide beneficial effects on maintaining optimum gut health. A few selected Bacillus strains promoted greater growth in chickens compared to AGPs, thus suggesting their potential as a replacement for AGPs. Furthermore, out of the ten different Bacillus strains, chickens fed with three strains, one B. licheniformis and two B. amyloliquifaciens, showed significantly higher body weight gains, reduced gut lesion scores and lower total fecal oocyst counts compared to non- Bacillus-fed control chickens. Bacillus-fed chickens showed significantly improved body weight gains after mixed coccidia challenge infection compared to non-Bacillus fed and coccidia challenged control group. These findings are promising and indicate the many beneficial effects of DFM in poultry diets to reduce the negative consequences of enteric diseases and to decrease economic losses imposed by coccidia infection in chickens.

Technical Abstract: The present study investigated the effects of dietary supplementation with several Bacillus strains on growth performance, intestinal inflammatory and anti-inflammatory cytokines, anti-oxidants and tight junction (TJ) protein mRNA expression in broiler chickens challenged with mixed coccidia infection (oocysts of Eimeria tenella, Eimeria maxima and Eimeria acervulina). Ten different Bacillus strains were screened for their beneficial effects on coccidiosis challenge by measuring relative body weight gain (RBWG), lesion score, and total oocyst count. Three out of ten Bacillus strains were evaluated in depth by measuring RBWG, lesion score, total oocyst count, and the gene expression of proinflammatory (IL-6 and IL-8), anti-inflammatory (IL-10 and TGF-ß), anti-oxidant (SOD1 and HMOX1), and TJ (JAM 2 and OCCLUDIN) proteins. Our results showed that out of the ten different Bacillus strains, chickens fed with three strains, one B. licheniformis and two B. amyloliquifaciens, showed significantly higher RBWG, lower lesion scores (caeca, jejunum, and duodenum), and lower total fecal oocyst counts compared to non- Bacillus-fed control chickens. Post-coccidia challenge, the RBWG for the Bacillus-fed groups were 95-100% as opposed to the control birds (70%) at 6 days post infection (dpi) and 10 dpi. Similarly, the lesion scores for three organs were around 0.8-0.9 for the Bacillus-fed groups as opposed to control birds (lesion score range ~1.4-2). The total oocyst counts were much lower in the Bacillus fed group (10-20 folds lesser) than the control group. Furthermore, the Bacillus-fed groups showed differential gene expression at 3dpi in different tissues, such as caecum, jejunum, and duodenum. Bacillus-fed chickens showed significant pro- and anti-inflammatory responses and higher expression of anti-oxidants and TJ proteins in the caeca, duodenum, and jejunum. Overall, our results demonstrated that dietary supplementation with Bacillus strains as direct-fed microbials (DFM) significantly improved the body weight gain after mixed coccidia challenge compared to non-Bacillus fed and coccidia challenged control group. In conclusion, the results of this study are promising and indicate the many beneficial effects of DFM-supplementation in poultry diets to reduce the negative consequences of enteric diseases and to decrease economic losses imposed by coccidia infection in chickens.