Alex, you should be more concerned about the slaughter of humans around the globe rather than the slaughter of animals.
If you can convince the masses to stop the first, your chances of convincing them to end the second increase.
Though it could be a hard sell. I love cow.
I'm concerned about both
All change starts from within. Volunteering is generally always a good thing. Doing something, helps in more ways than one.
I have and still do volunteer for a number of causes in the Seattle area. My concern for humans though is less due to the fact that in many cases humans have the ability to help themselves and control their own destiny whereas animals and our environment are at many times at our mercy. We experiment on animals, we use them as entertainment, and we enslave them for various uses. We pollute and destroy the Earth
due to humans misguided belief that we are the superior species that has dominion over everything. It it those areas of concern in my opinion that need to be changed, not my point of view.