Squealer, who is in charge of propaganda, insists that when good food goes to the pigs and dogs, everyone benefits. The pigs and dogs do very important work, they run the farm.
He also continues to remind the other animals that they receive more food than when Mr. Jones ran the farm.
Propaganda is a tool used by a totalitarian government to keep their people in line. This is used in conjunction with terror, censorship.
Squealer, who is known to be a persuasive talker, tells the other animals that it has been "scientifically proven that milk and apples are essential to the well-being of a pig". He reasons that since the pigs are the "brains" behind the management of Animal Farm, its whole existence depends upon them. He goes on to say that some pigs don't even like milk and apples, but they eat them for the good of the other animals so that they may be better able to carry out their very important duties - if they fail in this respect, Farmer Jones may come back! The animals are convinced by Squealer's argument, and the deception becomes practice without further opposition.
Squealer manipulates the other animals into thining that the pigs disliked milk with apples but they needed it in order to run the farm smoothly as it provided, and I quote 'brain power'. However all of this was mendacious and the pigs actually loved milk with apples. Squealer used his eloquence to convince the animals that Jones might come back if the animals did not give the pigs milk with apples as the pigs were the spearhead of the farm.