What events might have caused Old Major to gather the animals with the intention of telling them about his dream and introducing them to the song, "Beasts of England?"

I believe Old Major had called the meeting because he had noticed Farmer Jones was beginning to lack at performing his necessary duties. He was becoming a drunk, he had stopped feeding his animals, and stopped tending the farm's needs. Old Major must had been getting tired of all of the things Farmer Jones had been forgetting to do so he told the animals about the dream hoping that they would be able to fullfill his dream. Old Major had taught them the song hoping they would get it to other farms.