Emerging role of ruminal microbiota in the development of perinatal bovine diseases

As the largest and most important digestive organ of ruminant, rumen was a natural fermentation tank of dairy cows, in which there were many kinds of microorganisms. These microorganisms constituted symbiotic and complex ecosystems, termed as ruminal microbiota, which interacted with each other or cross-talked with the host to maintain homeostasis of host. In turn, ruminal microbiota could be affected by various factors, including host genetics, sex, age, diet and ruminal pH. Meanwhile, ruminal dysbiosis, especially caused by excessive consumption of a high-grain diet, was associated with the development of perinatal diseases, including subacute ruminal acidosis, systemic inflammation, mastitis, endometritis, liver diseases and laminitis. A better understanding of how ruminal dysbiosis affects the development of perinatal diseases may lead to novel strategies and treatments for perinatal bovine diseases. Hence, the purpose of this review is to summarize the latest studies discussing composition and regulatory factors of ruminal microbiota, highlight the relationship between the ruminal microbiota and perinatal bovine diseases and potential mechanisms, the model for studying the causality between ruminal dysbiosis and diseases, and the potential strategies to improve bovine health based on optimizing ruminal microbiota.