My daughter is two and although she won’t be asking questions or understanding death for a couple years yet
You might be surprised at what things a child will understand at what age.
I remember reading the book "Little House in the Big Woods," by Laura Ingalls Wilder aloud, and having a rather precocious 2-year-old come to me afterward for advice on butchering a teddy bear. We ended up with a plastic knife, and discussions like, "after it's dead, you cut off the parts you don't want to eat. That would be the head and the feet and..." That child wasn't much interested in the killing, just the details of how an animal would be turned into food. But I'm sure the child was under 3, had been listening and understanding the story, and "butchered" that teddy bear regularly for quite a while. I don't think that child properly understood about death, but they definitely were interested in how an animal gets turned into food.
I took it for granted that this would be a relatively easy concept but we processed our turkeys a couple of days ago and I find that I’m having a difficult time (I loved my boys) and realized how naive I was to think this would be an easy concept for a 3/4 year old


Looking for advice, dos and donts.
Since butchering doesn't bother me too much, I've been able to treat it like many other things, just one more part of the way life is. If I don't make a big deal about cleaning the coop or butchering chickens, a child will tend to assume the two things are equally important (or unimportant.)
I think my biggest tip would be to make it clear from the beginning, if the child shows any interest in the birds: "these cute little chicks will grow into big chickens, and then we will eat them and they will taste good." That means the child doesn't feel shocked or betrayed later, when it really happens. It's similar to many other discussions you might have with a child about what will happen-- "when these chicks grow up, they will lay eggs for us to eat" or "when this little plant grows into a big cabbage, we will eat it" or "first I put the cereal in the bowl, then I put in the milk, then you eat it" or "tomorrow we will go to the dentist, and he will look at your teeth." You just bring it up as it comes up, and they either discuss it or ignore it, depending on whether it interests them at the time.
If you read books aloud, you can choose some that include butchering animals as a normal thing, not a big deal.
I've had other times when a child wanted to watch the butchering, and thought it was really neat how the intestines wiggle and squiggle around (if you are fast enough about opening the animal up after it's dead, the internal organs may still be moving.)
I've also seen several children that were a bit curious, watched briefly, and then got bored and ran off to do something else. Among children who aren't upset, I think that is probably the most common reaction.
I've never dealt with a child who was very upset, but that may just be a coincidence.