So this is a huge thread and I am just looking through it. Could anyone give me a brief overview of the best ideas/techniques here for breeding resistance?
Also I see some have mentioned commercial layer feed being poor quality. What does everyone else feed instead? Do you buy some kind of expensive feed? Do you totally free-range? Mix your own feed? How do you know what you feed is better than layer pellets?
I think lalaland answered your post pretty well. What methods we use for breeding for resistance are going to differ between people. Diet is very important but even on the best diet weak genetics don't thrive. It's kinder to put an end to them.
When I can afford it I do mix my own feed, but lately that's been troublesome for me, I've had to use whatever I can get my hands on. Thankfully I've now got them freeranging again so they can be supplementing their own diet with what I can't provide.
How do I know what I feed is better than layer pellets? The results are really, REALLY obvious, you'll see the difference in their health and over a few generations the differences become more and more pronounced. When I first started out with chooks, I never used pellets. Only after a few floods and in emergency situations did I begin. At first, they would rather starve. New chickens I bring in, that have always been fed pellets, have always sworn off them for life as soon as I gave them an alternative. Never seen a single exception to that.
My chickens have always hated pellets and looked absurdly healthy. Having used pellets for a while recently I've watched their health steadily decline to the same anemic-skinned, mediocre-coated, desperate-appetite-ridden state I see most other people's pellet-fed chickens survive in. As lalaland said, surviving and thriving are two very different things. They still have sheen, and their faces are a shade of red, but it's not the bright, almost fluorescent cherry red I was used to, and their coats don't quite gleam as much as they used to. Soon as possible I'm getting them back off pellets.
I was aghast when I first joined this site and saw chickens everywhere that people thought were healthy but to me looked like they were dying. Pellet fed. It speaks for itself. >.>
To be fair, there are some very good quality pellets out there, but the overwhelming majority do not have access to them or the ability to afford them, or just don't know which brands they are. I don't have access to them so supplement. Most brands use hydrogenated oils; bad for us, as well as for chickens, no wonder liver disease and cardiovascular disease (including heart attacks and stroke) are so common among chickens. All for the same reasons it's so common among humans, same diet causes the same diseases.
Part of my method for counteracting the Marek's threat involves keeping old birds around the babies (no all-in, all-out, age segregation), and not rearing babies in sterile or even distant environments from the main flock... They get brooded and reared in the same dirt all the older infected birds are living on and have been living on for ages. Hence, heavily infected dirt. I do sometimes give them their own runs or temporary cages depending on circumstances, like having a staggered clutch or needing to adopt chicks out to a different mother from one that's not doing a good job, or having an injured chick so I need to slow down the mother's free ranging temporarily while it heals, but even then their mother will be shedding the virus so they are being exposed from day one. (Mostly I let my hens, those which I know are good mothers, free range as soon as they want, usually from day one, among the whole flock. Only bad mothers or emergency situations or unproven first time mothers get caged for a week or two to begin with).
I also lime the ground using calcium carbonate fairly often, once every few months, I suspect it helps control not just odor (as I use it as part of my deep litter method) but also the levels of coccidia and live virus in the soil. Maybe feeding garlic also has a knock-on effect via the feces as well, bumping up sulfur levels in the soil, or just harming the coccidia so efficiently it can't complete its lifecycle in any abundant numbers. There must be some reason I've been repeatedly doing, for years, exactly what experts reckon not to do, yet not losing a single chick to Marek's or coccidiosis, not even having any sickness in them.
Weak lines get culled and all their seemingly healthy relatives are under permanent suspicion until proven otherwise (which it seldom is). I keep records of even suspicions LOL. I never used to but soon found my subconscious was spotting things my conscious mind was logic-ing away, dismissing for lack of solid data, which could have saved me a lot of time, effort and lives to have paid attention to even if I didn't yet know the 'book learning' to support those theories or suspicions.
Mostly these days I just remove entire family trees if I found their descendants susceptible to disease. It's been a long time since that was necessary, so I know it works for sure. The most recent disease I'm working with is a genetically based one, an endocrine disorder in one family line. And genetic predisposition to scaly leg mite thanks to bringing in new blood again. It's been a long time since I've lost any, or even had any sickesses, due to any of the Marek's family disease complex.
Best wishes.
