Diet-induced changes in bacterial communities in the jejunum and their associations with bile acids in Angus beef cattle

Authors: LIU, JIANAN - University Of Maryland; LIU, FANG - Ocean University Of China; CAI, WENTAO - University Of Maryland; JIA, CUNLING - University Of Maryland; YING, BAI - University Of Maryland; YANGHUA, HE - University Of Hawaii; WEIYUN, ZHU - Nanjing Agricultural University; Li, Robert; SONG, JIUZHOU - University Of Maryland

Submitted to: Microbiome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2020
Publication Date: 9/16/2020
Publication URL: https://handle.nal.usda.gov/10113/7175913
Citation: Liu, J., Liu, F., Cai, W., Jia, C., Ying, B., Yanghua, H., Weiyun, Z., Li, R.W., Song, J. 2020. Diet-induced changes in bacterial communities in the jejunum and their associations with bile acids in Angus beef cattle. Microbiome. 2:33. https://doi.org/10.1186/s42523-020-00051-7.
DOI: https://doi.org/10.1186/s42523-020-00051-7

Interpretive Summary: The global demand for healthy and palatable beef products is rapidly increasing; and consumers are willing to pay a higher premium for grass-fed beef than grain-fed beef. In this study, we compared microbial composition and metabolic potential in the small intestine of grass-fed Angus cattle with those fed high-grain diets. Moreover, we examined the profiles of bile acids, which play important roles in animal nutrition and physiology, including attenuating inflammation, between the two beef cattle production systems. Our results suggest that the pasture (grass)-fed mode results in a significantly higher level of microbial diversity comparing to grain feeding. We also identified microbial signatures with a high predictive accuracy for bile acids. Our findings provided a better understanding of potential health benefits associated with grass-fed beef.

Technical Abstract: Background: The small intestine, while serving as the main absorption organ, also possesses a unique microbial environment and holds the critical function of conversion of primary bile acids. Bile acids are, in turn, able to regulate microbiome structure and promote the growth of bacteria that convert primary bile acids to secondary bile acids. However, in beef cattle, few studies have explored the microbial compositions of the jejunum and its relationships with bile acids. We hypothesize that microbial compositions in the intestine are influenced by diets and also related to bile acids. Results: We demonstrated that the dietary effect influences on the intestinal microbiome can be observed in early stages of young beef cattle, shortly after weaning. A significantly higher level of microbial diversity was evidenced in both the intestine and feces of grass-fed animals comparing to grain-fed cattle. Top 20 essential genera were obtained with random forest analysis on the fecal microbiome to identify candidate microbial biomarkers. Moreover, the jejunal microbiome of adult Angus beef cattle exhibited significant differences in microbial composition and metabolic potential under different diets. Global balances and microbial signatures of bile acids were identified. Conclusions: The findings from this study provided deep insights into microbiome compositions in fecal and jejunal and identified relationships between jejunal microbiome and bile acids with diets in Angus beef cattle. Our results should help us better understand grass-fed beef in production practice and potential health benefits.