Act utilitarianism, voting, and veganism

Singer, as an advocate of animal welfare, believes that you should practice veganism out or respect for animal rights.  But my decision to eat meat, or not eat meat, will have zero direct effect on the welfare of any animal. If I eat a steak dinner, the cow from whence the steak came was dead long before I chose steak over the veggieburger. But, you might say, I am voting with my dollars against the meat industry if I go for the veggieburger. But, would even a lifetime of veganism save so much as one animal from slaughter? If people in large enough numbers did what I did, then animal welfare might be affected, but the question "What if everybody did that" comes straight from Kant and is not part of at least act utilitarianism. (You can get to it through rule utilitarianism, however). But many things we do we do even though they will have little effect individually, but are still right because it would be good if everyone did them. Voting is a good example. I remember standing in a 3 hour line in the Presidential Preference Primary in Arizona to vote. It didn't affect the outcome, but if everyone refused to vote where would we be? One utilitarian of a previous generation said that he never voted, because the benefit from his voting did not outweigh the suffering he would endure standing in line.