Yes. I like the comic's art, but its content is pretty ignorant. Livestock animals have been selectively bred by humans to be of profit to us. They suffer all kinds of health problems because they are bred to be much bigger than their natural ancestors. Continuing to breed them serves no purpose, even if everybody was vegan there would be no logical reason to keep breeding these animals, knowing they will suffer health problems due to the manner of their selective breeding. But even if you disagree with that, and if you really think there should be these selectively bred species for whatever reason - that is no reason to also slit their throats. There are endangered species right now like pandas, tigers, rhinos and so on. Slitting their throats is no part of their conservation, and to suggest doing so would be ridiculous.
RE: Vegans destroying the planet?