He certainly was not. The propaganda spread was about him being a [b]vegetarian[/b], not vegan. And we have good reason to believe it was just that -- propaganda. Goebbels wanted Hitler to be seen as an advocate of peace, and a famous peace advocate at the time, Gandhi, was a vegetarian. Robert Payne, Hitler's biographer, has written about the man's love for pigeon and liver dumplings.

He did disapprove of animal cruelty, though.

Even if that's true and not propaganda, it isn't really relevant. You certainly can't make a coherent argument for abusing animals just because Hitler was against it.