Saying a prayer doesn’t change anything. You didn’t give the animal the best life you could. You gave it the best life until you decide you wanted to consume it for your pleasure. Not survival, pleasure.
And vegans are well aware that life consumes life. Vegans consume living things. They just don’t consume living things which are capable of terror or depression and suffering.
Say a prayer all you want, but harming an animal when you don’t need to is the act of abusing an animal for pleasure. I can say a prayer and be remorseful and thank a dog for its sacrifice after I put it in a dog fight and it got ripped apart, but that’s still animal abuse. It’s still wrong. And like eating animals in the developed world, it’s for pleasure.