There was a fair amount of interest and idea sharing from the last post and people offering their thoughts on what they thought the best solutions were to raising chickens naturally. We also received several requests to share the results (which we were planning on doing - but it is positive reinforcement that what we are doing is useful) - so here's the highlights. Out of dozens of responses, the overwhelming choice people made was to immunize their birds and let activity immunity play a role in keeping this particular disease out of their flock. The second most popular choice was do nothing and let nature do it's own thing. Nobody who responded thought antibiotics were a good solution towards prevention... wonder how many folks would use antibiotics if there was an outbreak. And then there were some pretty interesting "other" responses. And it's there I'd like to spend a little discussion time.
One of the most common (and I think universally misunderstood) solutions offered was to "breed in immunity". I hear and read about this concept all the time with regards to sustainable farming... and while that's a noble goal there are a lot of reasons why it just doesn't work the way people "think" it works. My favorite example of this comes from a large sustainable farm located in Georgia where they bought chickens from a hatchery, had one generation raised on their farm and then proclaimed - "We have bred in immunity to disease"... even better, they brought in some animals from another farm, converted them to a grass based diet and then - proclaimed they had successfully "bred in immunity". Huh - I thought breeding required reproduction...
The idea of breeding a more hardy (and hence disease resistance, healthier, able to fight things off better) breed is very common and has been practiced for centuries... but when it comes to Cornish Cross meat chickens, or many other hybrids it's not a truly viable goal. When you breed a hybrid (a cross between two different parent stocks where the end goal is to concentrate desirable characteristics in the offspring) one of the main characteristics the cross goes after is defined as hybrid vigor. Hybrid vigor is the term used to describe (in plants or animals) the F1 (first generation) cross that can usually be, as an entire population of the "child cross", construed to be "healthier", "bigger", "faster growing", "more vigorous". The one thing you DON'T get with a hybrid is the ability to breed them and have "true" offspring. So let's look at the Cornish Cross chicken example.
The common, broad breasted, fast growing meat chicken many, many farms raise in both the pasture and the CAFO models are Cornish Cross broilers. Contrary to the stories told by their detractors, they are created by the mating of male of a naturally double breasted Cornish strain chicken and a female of a tall, large boned strain of white Plymouth Rocks. Their offspring, the Cornish Cross, are F1 hybrids... their hybrid vigor is reflected in their massive breast size and their remarkable ability to convert food into flesh. However, should they be bred the resulting offspring of the 2 F1 (Cornish Cross parents) would be very, VERY different. (Breeding Cornish X birds is unlikely given their size, top-heavy nature and growth rates that make reaching maturity difficult). The point is - IF you could breed them - you would have F2 chickens (second generational crosses) that genetically were all over the place in terms of appearance, size and conformation - NOT the Cornish Cross bird you intended to have.
The point here is - should you want to try and breed for higher disease resistance you would first need to stick with lines that breed pure. Then, you would have to find a way to select for the required "resistance"... so - you would expose the birds to the pathogen and then breed only those that survived the experience. Then, breed and repeat. If you could find resistance (the inability to contract a pathogen) - you would then need to "test" for it in every new generation... And all that pathogen exposure results in a lot of loss as you are selecting for resistance... and resistance is NOT immunity. Whew.
Not sure I got the point across or not - but immunity is an active biological process that is triggered by the presence of a pathogen. Resistance is a genetic "change" whereby something about the resistant animal is different and the pathogen can't attack (great example Kelli gave - some people can't get HIV - their cells do not have the receptor the virus attaches to. They are not immune because their body isn't doing anything - they are resistant.)
Bottom line - you can't really breed in immunity... what you can try and do in pure lines is select for resistance.
There were a few other "other ideas" that were interesting but the last one I wanted to mention was a very informed response about homeopathy as a solution / alternative. Certainly there are some really good homeopathic preventative and acute treatment solutions out there (for example - we add Apple Cider Vinegar to the chicken waterers every few months to help with any parasites they might have ingested). The thing I though was really interesting was the proposed homeopathic solution for coccidiosis in chickens - various mercurial salts and sulfur. Basically it's a cocktail for a sulfonamide antibacterial.... which is the same basic chemical that farm stores sell to treat the disease. Sometimes homeopathic and "modern" medical solutions are the same chemicals - just a different name :)
(Before someone goes nuts out there - there are many different "meat breed" chickens that breed pure. So you certainly could breed and select for higher resistance... but they are different in taste, gain rates and conformation than the Cornish Cross. Thus far we have found several of those meat breeds to be very good for stewing, soup and boiling but our search continues for a fast growing ,tasty, good textured breed that can compete on a dollar for dollar and taste basis with the Cornish Cross.)