Dietary fibre supplementation promotes symbiotic interactions among the intestinal microbiota in preweaning calves

Dietary fiber plays a significant role in gastrointestinal health. In order to thoroughly comprehend the protective effect of dietary fiber on calf intestinal health, we conducted a randomized controlled trial with135 calves. We profiled the gut bacterial community in fecal samples from calves without diarrhea at five time points (0, 7, 14, 28, and 56 days of age) using both 16s amplicon sequencing and metagenomic sequencing. Our findings revealed significantly elevated abundance of Bifidobacterium and Prevotella in the intestine of calves fed with dietary fiber compared to the control group. Bifidobacterium and Prevotella may mitigate intestinal damage and protect intestinal health by modulating secondary bile acid metabolism and flavonoid metabolism pathways. Furthermore, CAZy differential analysis reveals that feeding different dietary fibers can induce increased abundance of CAZymes. We also found that changes in CAZymes abundance induced by feeding different dietary fibers are associated with distinct intestinal microbial communities. This suggests that feeding different dietary fibers stimulates the colonization of different bacterial species in the intestine, thereby increasing the activity of carbohydrate metabolism enzymes in the calf intestinal microbiota. This lays the foundation for health management in calves during transition period. Additionally, our research revealed that calves fed with psyllium husk powder at 56 days of age harbored intergeneric symbiotic clusters in their intestines consisting of Clostridium, Prevotella, Bacteriodes, and others. The symbiosis among these microbial species may collectively maintain intestinal micro-environment in calves. This study provides initial insights into the effect of dietary fiber on pre-weaning calf intestinal microbiota and lays theoretical groundwork for further research into this area.