Write what moves you emotionally. Believe that you can write something that will make yourself cry, and you will. Believe that you can surprise yourself with your writing, and you will. That astonishment will carry over to the reader.
Veganism is not exclusively for the overly-sensitive or for the people that grew up with glittery kittens on their school folders. It is a natural step we take when we start to act on our empathy. Veganism is morality in action. We stop supporting the exploitation of animals not because they are cute, cuddly, and silly, but because a difference in species does not translate to a difference in how one should be treated.