What is happening to the amount of food each animal receives?

George Orwell's Animal Farm is a novel famous for its satire and allegory. In the book, the animals working on Manor Farm get tired of the tyranny of their owner, Mr. Jones. Old Major, a pig, makes a speech about how all the animals should rebel against humans and take over the farm so that they can all be treated equally. After Old Major's death, the other pigs on the farm quickly put the ideas of his speech into motion. They start up Animalism, create Seven Commandments as the rules of their society, and run Mr. Jones out of the farm.
As the book goes on, things quickly go downhill as the pigs, the leaders of the animals, keep breaking and changing the Seven Commandments. Over time, the pigs take more and more of the farm's food for themselves, to the point where the other animals on the farm are starving.