Ruminants are mammals that can get nutrients from plant food by fermenting it in a special stomach prior to digestion, through microbial actions. Cows are a perfect example of ruminants. You have probably seen cows always chewing something. This is known as cud, which is regurgitated and chewed until it is completely fermented. This process of re-chewing food to break it down is called rumination.
Ruminants have a four compartment stomach -rumen, reticulum, omasum, and abomasum. In the first two chambers, the food is mixed with saliva and separates into layers of solids and liquids. Solids clump together to form the cud, which is further chewed to break it into smaller particles.
The capacity of an adult dairy cow’s rumen is about 184 liters. It is one of the most dense microbial habitats in the world. Microscopic organisms called rumen microbes break down the ingested feed by fermentation. The rumen is the major site of fermentation in the cow. Rumination can be affected by many external and internal factors. Cows prefer to ruminate in the evenings, in quiet, peaceful environments and they do this lying down. Rumination can be a very early indicator of stress or illness in cows. By monitoring decreases in rumination times, changes can be made to alleviate stressful situations.
For happy, healthy cows, ideal rumination is important in a stress-free environment.