This has been a really interesting thread. I think some of you are spot on and some have downright bizarre ideas of breeding for resistance. I think there needs to be a distinction between breeding for resistance in the truest since and simply breeding for strong stock (something somewhat intangible in that we don't know all the factors that make an individual strong or weak). In the strictest sense, breeding for resistance would (to me) be breeding for the genes that protect birds from certain diseases. There are a few known genes that do protect against some specific illnesses, but that discussion is probably beyond the scope of BYC (and it is beyond my current level of education, so I can't say that I feel confident discussing that topic in detail).
Edited by CityChicker - 9/19/10 at 5:14pm
There are probably multitudes of factors that make a flock strong and culling for that begins before and during incubation. This fact seems to be lost on many. I have raised birds since the 70's and have been working on a degree in Animal/Poultry science for a few years now in addition to coming from a family that has been in the business. The way that I was raised to do things is so far removed from the way I see people from BYC do things it is hardly even similar. I was taught to raise lots of birds and CULL, CULL, CULL. This holds true not only from a flock management/husbandry perspective, but also from a breed development/improvement perspective.
I have always been taught to only breed from the best stock possible. Set only the well formed and properly colored eggs. Do not assist in hatches. Raise only chicks that show signs of strength and vigor. Cull birds that do hatch, but show signs of any weakness. Definitely do not keep stock that shows signs of illness and NEVER shotgun medicate. As others have said, do not pass your problems on to other people. Cull the birds that are "weaklings". Constantly select for strong, vigorous birds. You don't want to keep the birds that were sick and recovered. You want to keep the birds that never got sick in the first place!
Anyway, all of this seems somewhat counter to the husbandry I frequently see practiced by BYC'ers. When my parents and grandparents were working with a particular breed, they would hatch, at a minimum, a few hundred birds each year in that breed and cull the heck out of them. For some breeds that we kept more for utility (another whole discussion that seems lost on a lot of modern poultry breeders), like the Plymouth Rocks, we would hatch several hundred in one season. My grandparents kept a stump with two nails and an axe in the middle of the yard (sound familiar, LOL). They would cull at the drop of a hat. I swear sometimes they would cull if a chicken just looked at them the wrong way, LOL. They also had incredibly strong and beautiful stock that also served its' purpose (again, the utility for which it was bred). They certainly never would have assisted hatches or made valiant efforts to save or nurture birds that were obviously weak in the first place.
This is what breeding for strong (and yes, probably "resistant") stock means to me. Whether or not, it is "resistance" in the truest academic sense, I am not sure. Day in and day out here on BYC, I see people do things that run completely counter to everything I have learned about poultry husbandry. This is another discussion that really makes me wish that BYC would have some sort of advanced topics board or something similar. As someone that has raised birds for decades, it is obvious to me when someone does not know what they are talking about (and there are a few on this very thread). It is less obvious to people that are new to the hobby. That is unfortunate as we have a number of outspoken "gurus" on BYC that know very little about poultry keeping.