Probably the most persuasive aspect of Old Major's speech is his description of what will happen to most of the animals before they reach old age. He was lucky enough to be allowed to live a long life, he says, but many of the animals will not be so lucky:
...no animal escapes the cruel knife in the end. You young porkers who are sitting in front of me, every one of you will scream your lives out at the block within a year. To that horror we all must come — cows, pigs, hens, sheep, everyone. Even the horses and the dogs have no better fate. You, Boxer, the very day that those great muscles of yours lose their power, Jones will sell you to the knacker, who will cut your throat and boil you down for the foxhounds. As for the dogs, when they grow old and toothless, Jones ties a brick round their necks and drowns them in the nearest pond.
Obviously, this passage underscores the basic dilemma faced by the animals, whose lives are only worthwhile inasmuch as they can serve human beings. Some, including the "young porkers," are only valuable for their flesh, and will die at the hands of man sooner than later. The animals no doubt would have found this very compelling. What makes it even more compelling in the larger context of the book is that ultimately, it is not Jones or any other human who sends Boxer off to the knacker when he gets old and infirm, but Napoleon. Overall, however, this is perhaps the most powerful part of the speech.