What Is a Ruminant?

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Ruminants: Cows, sheep, goatsA ruminant animal has a four chambered stomach in their digestive system. Livestock ruminants are cattle, sheep and goats. The different chambers in their stomachs allow them break down cellulose and utilize nutrients in grass and other tough vegetative matter. The 4 chambers are the rumen, reticulum, omasum and the abomasum and each of them play a different roll in digestion.

The rumen is the largest compartment of the stomach. Its main function is for fermentation of the animal’s diet. The rumen contains microbes that ferment and digest the contents making volatile fatty acids, which is then absorbed by the rumen. The rumen also contains small projections called papillae that line the rumen which creates more surface area for nutrient absorption.

The reticulum is located close to the animal’s heart and is connected to the rumen by a small fold of tissue. It has a lining that is shaped like honeycomb. The main function of the reticulum is to separate smaller digested particles from the rumen and move them into the omasum. The larger particles stay in the rumen for further digestion. The reticulum also collects harder and heavier foreign particles which can result in hardware disease. This can be a problem when animals eat foreign and metal objects. These objects can rub, irritate and puncture the lining of the compartment. Since the reticulum is close to the heart, there is a chance of these objects puncturing the heart.

The omasum has leaves of tissues that look like pages in a book. Stomach contents are worked in between the leaves where water and other substances are absorbed. This is where a majority of water absorption happens.

The abomasum or “true stomach” is the chamber that is most like a monogastric stomach. It is the only chamber that is lined with glands that producer hydrochloric acid and digestive enzymes that is used to breakdown stomach contents.

When ruminant animals are born, the esophageal groove prevents milk from going into the rumen. It allows the milk to go directly into the abomasum for digestion. As the animal gets older and they start to change their diet, their rumen develops and starts microbial growth. After this starts, the groove allows feed to go into the rumen for digestion.

The ruminant digestion process allows them to utilize feed sources that humans and non-ruminants can digest to turn in to food that humans can utilize (dairy and meat). Even though horses and other equine species eat grass as well, they are not ruminants. They are considered hindgut fermenters. Hindgut fermenters are able to digest plant cellulose by symbiotic bacteria fermentation in the cecum and small intestine.

Ruminates are designed to eat grass and other forages (roughage). Even though livestock are often fed grain, it is important that ruminants eat a well-balanced diet with lots of roughage when fed grain products. The roughage products keep the rumen healthy and producing those microbes to aid in digestion.