Ruminant Animals

Many different species of ruminant animals are found around the world. Ruminants include cattle, sheep, goats, buffalo, deer, elk, giraffes and camels. These animals all have a digestive system that is uniquely different from our own. Instead of one compartment to the stomach they have four. Of the four compartments the rumen is the largest section and the main digestive centre. The rumen is filled with billions of tiny microorganisms that are able to break down grass and other coarse vegetation that animals with one stomach (including humans, chickens and pigs) cannot digest. Ruminant animals do not completely chew the grass or vegetation they eat. The partially chewed grass goes into the large rumen where it is stored and broken down into balls of “cud”. When the animal has eaten its fill it will rest and “chew its cud”. The cud is then swallowed once again where it will pass into the next three compartments—the reticulum, the omasum and the true stomach, the abomasum

  

Four chambers of  a ruminant stomach

1.Rumen 

The rumen is the largest compartment within cattle’s stomach, with a capacity of 25 to 50 gallons depending on the size of the animal. This is the compartment that makes these animals so unique. This section of the stomach is home to billions of microbes that allow for the digestion of feed products that humans cannot digest. Bacteria, protozoa, and fungi are common families of microbes found within the rumen fluid. Without these microbes, the ruminant animal would be unable to utilize forages (such as hay) for energy as efficiently. Microbes are responsible for digesting cellulose and complex starches while simultaneously producing proteins, B vitamins, and vitamin K. Fermentation is the method of digestion that occurs within the oxygen-deficient environment of the rumen. The rumen tissue looks and feels similar to a shag carpet, as the inner lining is covered with projections called papillae. These papillae allow for more surface area to increase nutrient absorption

2.Reticulum

The reticulum does not have a clear separation from the rumen; thus, these two compartments often are called the reticulorumen. There is a small muscular fold between the reticulum and rumen, but it still allows digested feed to move unobstructed between the two compartments. The reticulum’s tissue has a honeycomb texture, which serves as “cups” to hold onto ingested feed. Cattle are indiscriminate eaters and often will swallow things they are not supposed to, such as screws, nails, bolts, and wire. These metal objects often find themselves in the reticulum and can cause hardware disease. This illness occurs when an object pierces through the reticulum wall where they can inflict damage on other organs such as the heart. To combat this, magnets can be placed into the animal’s reticulum to catch metal pieces before it occurs.

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3.Omasum

As feed leaves the reticulorumen it moves into the omasum. Given the large amounts of water and rumen fluid that leave the rumen, it is important that the omasum comes next. The omasum is responsible for absorbing water from the ingesta. The omasal tissue has a series of folds covered in small papillae. This texture is why many people call the omasum the “butcher’s bible,” as the folds look like pages from a book when put together.

4.Abomasum

The abomasum is most similar to a human, or monogastric, stomach. This compartment is often referred to as the “true stomach,” as it contains hydrochloric acid and enzymes, much like our stomachs. This compartment prepares the nutrients for absorption by the small intestine. The tissue has smaller folds when compared to the omasum and is smooth and slippery. Mucus is secreted from the tissue’s surface to protect it from the acid produced, and this mucus is what gives the tissue a slippery feel.