Maternal Fecal Microbes Contribute to Shaping the Early Life Assembly of the Intestinal Microbiota of Co-inhabiting Yak and Cattle Calves

Abstract BackgroundLong time exposure to seasonal forage availability and harsh environment on the Qinghai-Tibetan Plateau (QTP) has resulted in a series of unique adaptation mechanisms following the evolution of yak to cope with nutritional deficiencies and other adverse conditions. This is likely achieved by an unprecedented genetic resource for fibrolytic enzymes of microbial origins that allow the host to efficiently degrade plant polysaccharides. However, to what extent of maternal symbiotic microbial transmission throughout early microbial successions and its adaptation to high-altitude hypoxia in grazing yak driven by the harsh environment and nutritional stress have been far from clear. Understanding the colonization and succession of yak gut microbiota would help to clarify the functional interaction and crosstalk between microorganisms and their hosts. This study explored the succession of intestinal microbiota of yak ( Bos grunniens ) and cattle ( Bos taurus ) kept in the same habitat during pre-weaning period. ResultsThe gut microbiota of yak and cattle calves were dominated by members of the families Ruminococcaceae , Lachnospiraceae , and Bacteroidaceae during pre-weaning. Moreover, source-tracking models revealed that maternal microbiota was critical for the rapid establishment and colonization of initial intestinal microbiota of their calves at development stage and its impact persisted until weaning or even longer. Compared with cattle calves, the gut microbiota of yak calves was rapidly established and reached to a relatively stable status at the 5th week after birth, indicating the evolutionary significance of interaction between the yak and its intestinal microbial community that could facilitate the adaptation of this flagship species to adapt to the harsh environment on the QTP. ConclusionOur results revealed that under natural grazing conditions, the calves raised by their mothers acquire gut microbiota through the contacts with maternal feces and the social learning behavior, which accelerate the establishment of stable intestinal microbiota. In addition, after long-term natural selection, the yak calves acquire a relatively mature and stable intestinal microbiota earlier than the cattle calves, facilitating their strong adaptation to the harsh environment on the QTP.