i think in general, it's always a good idea to not make pets out of meat animals. keep them separate, make no attachment emotionally, whether it is your kids or yourself.
little kids don't need to see the animal die to know where it comes from. they should only watch the dying process if they are comfortable and when they are comfortable with it. curiosity will draw them to the processing part (to see what the heart looks like, the gizzard, liver, etc), when they are ready.
to make someone watch when they do not want to, is not necessary. some adults are too squeamish, and that's fine, too. i see the cow eat hay and corn and the poop is the result, i don't need to see the actual inner workings of the cow
if they want to watch, let them watch (i would let a 5-year-old, but your kids are old enough). if they don't want to, i don't think you should make them. making someone watch reminds me of those old movies where a person is tied to a chair with their eyelids taped open, watching propaganda brainwash movies
to me, knowing where your food comes from is more from feeding and tending the animals, than the actual processing