Effect of high proportion concentrate dietary on Ashdan Yak jejunal barrier and microbial function in cold season

The intestinal health of ruminants plays a vital role in absorbing and metabolizing nutrients. In order to explore the jejunal barrier and microbiota dysfunction of Ashdan yaks, animals were fed with a high proportion of concentrated feeds in cold season. In present study, twelve Ashdan male yaks were arbitrarily separated into two categories, namely FF and CF. Compositional and functional differences in their jejunum barrier and microbiota between the FF and CF yaks were compared using metagenomics and proteomics methods. The results showed that the activity of jejunum digestive protease and microbe metabolite of forage-fed yaks were more conducive to healthy cultivation than the concentrate-fed yaks. 57 differentially expressed proteins (DEPs) were recognized using label-free MS, those could conclude to 2 principal classes: structural proteins and inflammatory factors, and 14 proteins were relatively active in those principal classes. Firmicutes were the dominant bacterial phylum in the jejunum microbiota of both the forage-fed group (24.33%) and concentrate-fed group (23.16%). As compared to forage-fed group, the concentrate-fed group showed enhanced alpha diversity and reduced beta diversity of the jejunal microbiota. The long-term high-proportion concentrate feeding inhibited the growth of Actinobacteria, Proteo-bacteria, Ascomycota, Bacteroidetes and stimulated the growth of Streptophyta, Cyanobacteria, Fusobacteria and Chlamydiae. The concentrate-fed group showed increase in the abundance of immune system process, along with decrease in the metabolic process, especially the binding process. Interestingly, the proteomics and metagenomics results were both inclined to the enrichment of jejunum mechanical barrier and inflammatory response. Overall, the study suggested that the long-term high-proportion concentrate feeding affected the expressions of specific jejunum proteins and composition of microbiota, which damaged the jejunum barrier and the function of microbiota in yaks.