Bob good for you don't give your kids meds if they don't need it, they rarely do. I put my chicks outside immediately. What's healthier, a kid laying around watching TV all day, or one running around in the sunshine swinging on trees..yup kids get dirty so do chickens. The graduated immunity is like this, you get a very small exposure over a period of time...how to keep it a small exposure, why easy, don't confine them in a poop ridden environment with a ton of wet manure. If they have sunshine, fresh air, grassy run they will thrive.. when the chickens contact a tiny organism the immune system recognises it as an intruder and builds a specific white cell to eat it, next time it gets that bug the immune system is already prime to attack it and doesn't waste time wondering what it is. Problems occur when the initial contact is too much/many for the immune system to gear up, build cells before the germ multiplies, or when the initial exposure doesn't cause the immune system to recognise a threat because it is hampered by medications, meds that are doing what the immune system should. I don't want weak immune system chickens, if they die, well, nature had her way. Large chicken factories cannot afford to loose alot of birds, so they use preventative antibiotics....they only keep that chicken for a short time and don't consume it..the general public feeds medicated because they asked for it and it was supplied. You know its unfortunate but one of the worst bugs has been mutated by humans for humans because people demand rx from their doctor when its unneccesary, and then don't take it as prescribed....most medical people do not want to treat this way but people expect to leave with a rx and really raise hell when they don't. So, why argue... Vaccinations on the other hand, expose the body to a usually simulated form of the disease they are attempting to eradicate, in an attempt to stimulate the immune system to produce antibodies against that specific threat, so when it does get actual exposure it is ready to go immediately into action, no lag phase. Taken correctly it is quite effective...think smallpox..however, vaccinations can have bad affects, including death which happened alot with that particular vaccine. Giving medication, especially in subterapeutic doses, can actually cause mutations in that bug, and now it is primed and ready to over whelm the body even when now medicating against it....now, life vrs death, can you think of a particular virus that humans have allowed to flourish and found a way to keep it alive in a host indefinelty? Scary scifi stuff that is reality.
