The Role of the Rumen Microbiota in Determining the Feed Efficiency of Dairy Cows

Dairy cattle hold enormous significance for man as they convert the energy stored in indigestible plant mass into milk and meat, which are digestible and consumed worldwide. The efficiency with which an individual cow converts the energy stored in its feed into food products, termed feed efficiency, is thought to be stable; however, for reasons poorly understood, it varies considerably between cows. One factor that could markedly affect dairy cow feed efficiency is its residing microbiota which, in ruminants, is responsible for most of the food’s digestion and absorption. The microbes are mainly situated within the first compartment of the digestive tract – the reticulorumen. Recent studies connecting methane emission, clustering, and diversity of microbial populations with the cow’s feed efficiency strongly imply that the reticulorumen microbiota is correlated with cows’ energy utilization. Hence, understanding the relationship between the reticulorumen microbiota and cows’ feed efficiency may favor more energy-efficient microbiomes, and therefore increase fiber degradation, elevate reticulorumen microbial protein concentration, reduce methane emission, and consequentially improve cow productivity.