The early impact of genomics and metagenomics on ruminal microbiology.

Knowledge gained from early and recent studies that define the functions of microbial populations within the rumen microbiome is essential to allow for directed rumen manipulation strategies. A large number of omic studies have focused on carbohydrate active enzymes either for improved fiber digestion within the animal or for use in industries such as biofuels. Studies of the rumen microbiome with respect to methane production and abatement strategies have led to initiatives for defining the microbiome of low- and high-methane-emitting animals while ensuring optimal feed conversion. With advances in omic technologies, the ability to link host genetics and the rumen microbiome by studying all the biological components (holobiont) through the use of hologenomics has begun. However, a program to culture and isolate microbial species for the purpose of standard microbial characterization to aid in assigning function to genomic data remains critical, especially for genes of unknown function.