Not all animals digest food in the same way

For example:

Chickens, cows, pigs do not eat the same food. These animals have different stomachs; they do not digest in the same way. That is why they do not eat the same things.

Sheep, goats and cows eat the same food. These animals have the same stomachs.

Chickens and ducks eat the same food.

Pig stomach; cow and goat stomach

In one and the same herd of cattle there are often animals that eat the same food but do not grow in the same way.

They eat the same food and have the same digestive tract, but some use their food better than others.