Nancy Knapp, Age 11, Of Exeter, Calif., for her question:
Why does a cow need four stomachs?
Bossy, the farm cow, has really only one stomach, but it is divided into four parts. She uses her fancy stomach to swallow mouthfuls of grass, and later she coughs them up and chews the cud. The farm cow inherited her special stomach from the wild, cattle who were her ancestors. And they needed it to save themselves from their prowling enemies.
A cow in the pasture seems to spend most of her day dining. First she ambles around lazily gathering mouthfuls of grass and swallowing them whole. The unchewed the food goes down into the rumen and the reticulum, first room and the second room of her stomach.
When they are filled, the cow strolls to some quiet place and takes life easy while she chews the cud. She brings up a wad of unchewed food with a little hiccup and uses her sturdy molars to grind it to pulp. The owl is now ready to be swallowed again. Down it goes through the rumen and the reticulum into room three, which is the omasum.
In the omasum some of the juices are squeezed out from the food. The pulpy mass then goes to the omasum, where it is doused with digestive juices and broken down into nourishing chemicals. After a few hours of chewing one cud after another, the cow is ready to graze again.
The farm cow does not need to spend all this time dining. But she must use this method of digesting her food because of the four part stomach she inherited from her wild cattle ancestors. All of our domestic animals descended from wild ancestors, and the ancestors of the cow were grazers who roamed the grassy plains and wooded slopes in ancient times.
They shared their lands with hungry meat eaters. The grazing herd was hunted by wolf packs and giant cats. Most of the cattle could outrun their enemies over a long distance. But it was not easy to graze and watch for danger at the same time.
The wild cattle learned to keep out of sight. They came into the open only in the dim light at dawn and sunset to grab a quick meal and swallow it whole. Later they hid. Among the trees and shady shrubs while they took time to chew the cud. The cow in the pasture is not threatened by prowling meat eaters, and she does not need to grab a meal and chew it in hiding. But her ancestors needed that special four room stomach, and, the cow inherited it.
The cud chewing animals are called ruminants because the first chamber of the stomach is called the rumen. Our domestic cattle, the cows, sheep and goats, are all ruminants. The camels of the deserts and the patient llamas of South America are also ruminants. The tall giraffe, the deer and the graceful antelopes are ruminants that still enjoy life in the wild. Like the ancestors of the farm cow, these wild ruminants need their special stomachs to grab a quick meal and hide from their enemies.