what is replaced in the new song and how does it affect the idea and vision of old major?

Squealer arrives with a dog escort and forbids the animals from singing the anthem, for Napoleon has abolished it. He explains that the Rebellion has now ended with the slaughter of the unfaithful and that, being a song of the Rebellion, “Beasts of England” has no further purpose. The animals are now to sing Minimus’s anthem, which begins with the lyrics: “Animal Farm, Animal Farm, / Never through me shalt thou come to harm!” This new song undermines what Old Major's original vision was.