- Animals: bovine
- Animal Production: animal protection and health, probiotics
Calf diarrhea is one of the biggest challenges in both the dairy and beef industry worldwide. In the U.S., between 4 and 25 percent of calves die from diarrhea each year. The increased intestinal permeability and disturbance of gut microbiota are key factors leading to the pathogen-induced diarrhea. Brahman cattle contribute substantially to beef production in the southern regions of the US through crossbreeding, due to their heat tolerance and disease resistance. The heat stress can induce the damage of intestinal barrier dysfunction, but it is largely unclear whether the heat-tolerant Brahman calves have a more integrated intestinal epithelium that contributes to their resistance to diarrhea. Our preliminary studies found that fewer pathogens and mucin-degrading bacteria but more beneficial butyrate-producing commensals colonized in the gut of preweaning Brahman calves compared with Angus calves. Fecal microbiota transplantation from diarrhea-resistant livestock has been reported to relieve diarrhea of recipients. Here, we raised a hypothesis that gut microbiota of Brahman calves contributes to diarrhea resistance and strong intestinal mucus barrier through suppressing pathogenic bacteria and mucin-degrading bacteria. In this project, we first evaluated the differences in gut microbiota structure between Brahman and Angus cattle throughout the production lifecycle using a cohort multibreed Angus-Brahman (MAB) herd using the 16S rRNA gene sequencing. Consistent with preliminary studies, the beneficial butyrate-producing bacteria were enriched in cattle with more Brahman composition. Meanwhile, we collected the fecal samples from 91 3~5-week-old beef calves, and conducted 16S rRNA gene sequencing to understand the differences in gut microbiota composition between healthy and diarrheic calves. We found that the diarrheic cattle contained less diverse gut microbiota and harbored less relative abundance of butyrate-producing bacteria, such as Roseburia, Faecalibacterium, and Odoribacter, but higher abundant pathogens, including Campylobacter and Fusobacterium. Bacterial strains were isolated from preweaning calves, and one of them were characterized as a new bacterial species as Streptococcus vicugnae. These results shed light to reducing the calf diarrhea by promoting the diversity of gut microbiota and developing probiotics from butyrate producers.
- To compare the gut microbiota composition between disease-resistant Brahman cattle and fast-growing Angus cattle
- To Characterizing the gut microbial composition and function between healthy and diarrheic calves
- To isolate potential probiotic strains from diarrhea-resistant Brahman calves and test their antimicrobial activity
- To evaluate the efficiency of potential probiotic strains on the reduction of diarrhea and investigate its functional mechanisms in terms of regulation on the gut microbiota structure and intestinal mucus barrier function