Impact of Subacute Ruminal Acidosis (SARA) on Ruminal Microbiome, Lipopoly saccharide and Bioamine and Rumen Epithelial Health of Dairy Cows

Maximizing milk yield without impairing host health is a great challenge for dairy industry. However, the high concentrate feeding often unavoidably increases the risk of Subacute ruminal acidosis (SARA) in dairy cows, characterized by periodic episodes of low ruminal pH. The economic costs caused by SARA are enormous, while its pathogenesis is not very clear. As the first and the main digestive compartment, the rumen health during SARA has received much research effort in recent years. There are increasing evidences showing that the effects of SARA on rumen are multifaceted and detrimental. To address this issue, this review summarized the impact of SARA induced by high-concentrate feeding on gastrointestinal microbiota, ruminal fermentation, and its role in damage to the ruminal epithelium and host function in dairy cows. Further experimental work is required to elucidate the mechanisms by which high-concentrate feeding induces ruminal epithelial barrier dysfunction, as well as the relationship between ruminal epithelial barrier dysfunction and high concentrate diet-induced metabolic disease, which seem to be of great importance for preventing these diseases.