In fact, millions of tiny organisms (mainly bacteria) naturally live in the rumen and help the cow by breaking down plant parts that cannot be digested otherwise. A cow’s rumen is different because it functions like a large food processor. With a simple stomach, the dog, and even man, cannot digest many plant materials. The reticulum (letter B, Diagram 1) is sometimes called the “honeycomb” because of its distinct honeycomb-like appearance. The reticulum is made of muscle, and by contracting, it forces food into the cow’s esophagus which carries the food back to the mouth. The reticulum is directly involved in rumination. This process of swallowing, “un-swallowing”, re-chewing, and re-swallowing is called “rumination,” or more commonly, “chewing the cud.” Rumination enables cows to chew grass more completely, which improves digestion. This is true, but cows are able to voluntarily “un-swallow” their food. “But they have already eaten,” you might be thinking. After filling up on grass, cows find a place to lie down to more thoroughly chew their food. In a mature cow, the rumen is about the same size! Its large size allows cows to consume large amounts of grass. Cows are known as “ruminants” because the largest pouch of the stomach is called the rumen. This is a characteristic feature of the digestion in cows. When a cow first takes a bite of grass, it is chewed very little before it is swallowed. See how many more structures there are in the cow’s stomach? In the cow, rather than having a single pouch, there are four interconnected pouches, each with a unique function. Notice that the letters do more than identify the structures they also map the path food travels on its digestive journey. Use the letters that label the stomach parts in Diagrams 1 and 2 to identify the similarities and differences between the two stomachs. On the right, a cow’s stomach is shown in Diagrams 1 and 3, and a dog’s stomach is shown in Diagram 2. The Stomachĭ = Omasum E = Abomasum F = Small Intestine BeginsĪ = Esophagus E= Stomach Body F = Small Intestine BeginsĪll three diagrams courtesy of Sudz Publishing Plant materials sometimes contain tough stems, but because a cow chews food in a side-to-side motion, the molars shred the grass into small pieces that are more easily digested. Teeth in the back of the mouth (known as molars) are located on the top and bottom jaws. Because of this unique oral anatomy, a cow uses its tongue to grasp a clump of grass and then bite it off. In addition, cattle have a relatively immobile upper lip (compared to goats and sheep). In place of the top incisors, there is a hard leathery pad (known as the “dental pad”). In the front of the mouth, teeth (known as incisors) are only located on the bottom jaw. EatingĬows are unique in that they have fewer teeth than other animals. This basic digestive process is also true of cows, but there are a few extra steps along the way. Next, food passes into the small intestine where the breakdown continues and where the body absorbs nutrients. After we chew and swallow our food, the stomach serves as a holding tank where digestion begins and food starts being separated into individual nutrients. The key to this ability lies in the stomach. Let’s explore how cows are able to eat grass. Cows, for example, have a very different digestive system than our own, and this allows them to thrive on a menu predominantly made up of grass. Digestion is the process our bodies use to break down and absorb nutrients stored within food, but the ability to digest food is not the same for all animals.

2022.09

Don t go into the long grass