I think there are a lot of people who out of a well meaning compassion for animals get fooled into the idea that every living creature must be saved and nursed back to health. That is fine if the animal is your personal pet that you or your family has bonded with but it can be a detriment when it comes to breeding and improving the species/breed. I can't speak for hatcheries breeding practices or any chicken breeders for that matter, but I have witnessed goat breeders who medicate and vaccinate their breeding stock. While they test and cull for contracted diseases, I always felt that all the medicating could definitely be masking weaknesses that could have otherwise been selected against which in the end would completely negate the pharmaceutical approach to raising healthy animals.