This is a very timely post for me. (I'm not about to wade into the kosher/halal debate)
The other day my family went and bought some rabbits for the freezer. We stopped on some crown land to clean them. My oldest boy is 8. He loves animals, and has helped raise rabbits, snakes and guinea pigs at home, and has helped or at least been present while we butcher deer. He picked up a brown rabbit out of the cage and kept petting it, and asking if we could keep it. While I killed and cleaned the first one, my wife took our sons for a walk. They came back as I was finishing the first one, and my oldest son was right into the van with this brown one out of the cage on his lap.
When the time came for the brown one to be done, I offered to let him go for another walk with his younger brothers but he didn't want to go. So I made sure he knew what was coming, and offered to let him stand on the other side of the van if he wanted. He said he understood what was happening and was interested in watching. I explained the twitching after death, then we hung it and cleaned it, and I explained what I was doing, pointed out the organs and their function etc.
A little while later he says "Dad when I have kids I don't think I'm going to kill stuff in front of them". I told him it was OK to be sad after watching something die, then I let him digest what he had seen for the rest of the day.
At dinner, I brought the subject up again. I explained to him that while he doesn't need to go out and kill his own meat if he doesn't want to, it's important to understand where meat comes from. The sausage he was eating was a pig at one time. The hamburgers he loves used to be cows etc.
I told him that killing something shouldn't bring you joy, but enjoying meat comes at a price and it's important to understand what that price is. I also explained that we did it as quickly as we could, and we made sure nothing was wasted. We didn't do it at home where the entrails would be put in landfill, but took it out to the bush where other critters will make a meal of what was left.
I work with a lot of tree huggers. They aren't necessarily anti hunting, they just couldn't stomach doing the deed themselves. What I found really interesting is that after relating this story at work, most of them were freaked out at first that I would let an 8 yr old witness that. After hearing the dinner conversation, many of them commented that they almost wish they had been given the same lesson when they were young.