The Effect of Rumen Microbiota in The Susceptibility of Subacute Ruminal Acidosis in Dairy Cows

Abstract Background: Subacute ruminal acidosis (SARA) is a well-recognized metabolic disease that has negative impact on the animal performance and health. SARA in cows is mainly caused by long-term high-concentration diet (HCD) feeding, however, some cows are so well adapted to the HCD that do not develop such condition while others are more susceptible. We speculated the difference may be associated with the rumen microbiota community. Here, we analyzed the rumen bacterial and fungal microbiota from SARA-resistance and SARA-prone cows before and after feeding with HCD for six weeks. Results: The 16S rRNA sequencing analysis showed that the rumen bacterial community in SARA-prone cows had lower bacterial diversity and higher relative abundance of unidentified_Spirochaetaceae and Anaeroplasma comparing to those of SARA-resistance cow. Moreover, the abundance of Stenotrophomonas were increased in SARA-positive compared to SARA-negative cows. In addition, the ITS1-IF sequencing analysis indicated that the abundance of Fusarium_oxysporum and Papiliotrema_laurentii were different in SARA-prone and SARA-resistance cows. Furthermore, feeding with HCD significantly increased the Sarocladium_zea , Meyerozyma_caribbica , and Fusarium_oxysporum , while decreaed Wallemia_sebi in rumen microbiota. These results suggested that the abundance of unidentified_Spirochaetaceae , Anaeroplasma , Fusarium_oxysporum, and Papiliotrema_laurentii in rumen maybe connected to the susceptibility of SARA in dairy cows. In addition, SARA provocation was increased the pathogenic Stenotrophomonas, Sarocladium_zea , Meyerozyma_caribbica , and Fusarium_oxysporum in rumen. Conclusions: This study suggested that manipulating rumen microbiota will serve as a novel approach for preventing the development of SARA in dairy cows in future studies.