When you talk about feeding ruminant animals, what you’re really doing is feeding the microbes in the rumen. And when you think about nutrient requirements for cattle, you first need to ensure that the nutrient requirements of the microbes are met so that they can do their job.

That’s how Janice Bowman, Montana State University professor of animal and range sciences, explains the science of feeding cattle.

Bowman says there are numerous species and types of bacteria, protozoa and fungi present in the rumen, all with different characteristics. The presence of these various microbes and their affinities for different feed ingredients is a key reason why ruminants can successfully live on both high-roughage and high-concentrate diets.

Each microbial species is specialized in what it consumes and produces, and how it will interact with other microbial species during digestion. A diverse and well-balanced diet will result in a more diverse microbial population and, consequently, a more efficient rumen.

“The rumen is really a fermentation vat that is constantly churning its contents; larger particles are retained in the rumen for more digestion, while smaller particles are flushed out. Tiny finger-like projections, called papilla, on the rumen wall increase the surface area and, thus, the absorptive capacity of the rumen itself,” explains Jeff Carter, ADM Alliance Nutrition beef nutritionist, about rumen anatomy and function.

To help ensure a healthy rumen environment, Dan Wolf, ADM Alliance Nutrition sales representative, suggests feedlot managers implement a strategic deworming program, maintain adequate fiber in the diet and provide a balanced mineral appropriate for the overall diet.

Bowman notes that during the digestion process, microbes are responsible for producing volatile fatty acids, which are the source for 70%-80% of the animal’s energy. Finding ways to maximize efficiency and digestion of individual rumen microbes results in better animal performance.