For chickens, rice and wheat are really “delicacies”. However, even if you feed on these foods, they will still peck around looking for small stones or grains of sand to eat.
Why do chickens have this quirk? In fact, it’s not because chickens like to eat pebbles, nor because chickens have a strange stomach that can digest gravel, but because they use gravel to help digest food.
As we all know, we humans, cats and dogs and other animals, before food is digested in the stomach, always chew it with teeth. However, chickens, like other birds, have no teeth and need to rely on other things to help grind food. Small stones play such a role.
When we kill chickens, we can find a part of chicken gizzard, which is called muscle stomach or sand sac in zoology. Many small stones are stored in chicken gizzard. Chicken gizzard is very tough, and the inner wall of chicken gizzard has a layer of yellow and tough wrinkled skin.
When the food goes into the gizzards, they mix with the pebbles. Chicken gizzard is a bag made of only thick muscles. Under the strong peristalsis of chicken gizzard, squeeze, grind, the edges and corners of sand and stone rub the food. After a while, the food will be ground into broken paste!
What’s more, before entering the chicken gizzard, food has been stored in the crop (most of the esophagus) and the glandular stomach (a stomach in front of the chicken gizzard) for a period of time. Under the action of various digestive juices, the food is initially “processed” into soft food.
Among animals, not only chickens have the habit of eating pebbles, but also pigeons and other birds.