What act do the pigs do that upsets the other animals? How does Squealer persuade the other animals that is really fair?

I don't see this in chapter 4. In Ch. 3 the pigs seem to be taking the milk and apples every day, but explain that this is only because it is their responsibility to maintain their health. They don’t even like milk and apples, they explain. In Chapter 8 Squealer explains the lopsided rations as a readjustment.