人们大量地饲养家鸡,以获得鸡肉、鸡蛋或鸡的羽毛。通常人们都用稻谷、麦粒等谷物和剩饭喂养家鸡,可鸡却常常吃些小石子儿,这是为什么呢?原来,鸡的嘴里没有牙齿,不能磨碎食物,只能把食物整个地吞咽下去,这样,食物就不容易在胃里消化。于是,鸡会不时地 People bred a large number of chickens for chicken, egg or chicken feathers. Usually people use rice, grains and other grains and leftovers to feed domestic chicken, chicken but often eat pebbles, which is why? The original chicken’s mouth without teeth, can not be ground food, only the whole food Swallow it, so food is not easy to digest in the stomach. So, chicken from time to time