Rumen Function



Rumen Function

The rumen is essentially a fermentation chamber where plant fiber is broken down into smaller digestible components by bacteria and other microbes. The rumen cannot function correctly without a healthy and active microbial population. If the feed does not contain the right balance of ingredients, the microbial community will be thrown out of balance. For instance, if the diet contains too much rapidly fermentable carbohydrate, the population of lactate-producing bacteria will rise. Consequently the pH of the rumen will drop, decreasing the number and activity of lactate-utilizing bacteria. This can result in a further drop in pH and acidosis. This is just one possible result of an imbalanced microbial community in the rumen.

To feed cattle properly you must feed the rumen microbes. They need the proper mixture of fiber, energy, nitrogen and water. Particle size is also important because long fibers are essential for development of a functional rumen mat. The mat helps retain finer ingredients in the rumen long enough to be fully fermented and it encourages cudding, which helps break down fiber and increases production of saliva. Saliva buffers the rumen, keeping the pH from dropping and maintaining a healthy microbial environment.

Rumen bacteria are anaerobic with varying degrees of sensitivity to oxygen. When cattle eat forage, oxygen enters the rumen. This is unavoidable but an appropriate yeast culture can help maintain anaerobic conditions by consuming oxygen in the rumen. These bacteria also consume sugar, which slows the growth of lactate-producing bacteria. This helps to stabilize the rumen pH.

Rumen bacteria have another important job besides breaking down fiber. They are eventually carried out of the rumen and into the abomasum where they act as the primary source of protein for the animal as they are digested. It is therefore important that they have a consistent and available source of nitrogen for growth. Too much nitrogen and they produce excessive amounts of ammonia, which can be very harmful. Everything has to be in balance in the diet in order to achieve balance in the rumen microbial community.

Beef Cattle Challenges