Hi Ki4got,
I'm so sorry that you lost those chicks. When chicks have that much potential, it hurts our breeding program, and our hearts.
Have you sent them in to be necropsied (an autopsy, but for animals)? That can sometimes give you important answers. It can be done quite cheaply in many areas of the country, where it is often subsidized by either private industry (which doesn't want a multimillion dollar chicken industry wiped out by a contagious disease from someone's backyard flock) or by the dept. of agriculture. You can contact the Virginia Tech, Virginia-Maryland Regional College of Veterinary Medicine (540-231-7666, talk to the pathology dept first, then if needed the poultry science dept), or your state dept of agriculture, or your county agricultural extension office to see who could do the necropsy and what your cost would be. The last chicks I had done were only $10, and the necropsies were very thorough. If you do want to have them necropsied, put them in the refrigerator immediately (not the freezer), and transport them to the necropsy facility ASAP in a cooler with ice packs. The necropsy will be less accurate with every day that passes, so this is very time sensitive.
If I understand the situation properly, you had a larger number of chicks (how many chicks total?, all the same breed? all the same age?) in a grow pen with green forage (but not free range yet), and you lost all 4 (2 male, 2 female) of the 5 wk old chicks out of eggs you got from Rudy. None of the other chicks were sick or died, but all of the "Rudy chicks" died. They were being fed 20% chick crumble from a small mill that does not produce medicated feed (which likely rules out accidental poisoning from the mill). They were normal until 24 hours or less prior to death, and were not sickly chicks that had been growing poorly. Their symptoms shortly prior to death were vocalizing, hunching, and lethargy (painful?). And you are an experienced chick raiser that has hatched and raised hundreds (?) of chicks successfully.
If the above circumstances are accurate, then it is not reasonable to blame this on nutrition. It is standard to raise chicks on 14-24% protein, with different levels being used for different purposes, different breeds, and different ages. (I know that many people will strongly disagree with my range -- that's ok. Anything outside of 16-20% is usually for very specific goals.) But regardless of your "protein philosophy," you don't see acute death in multiple birds by feeding slightly above or slightly below some "ideal" level.
If the only thing that all the affected birds had in common, and all the unaffected birds did not share, was that they were hatched from Rudy's eggs and that they have died, then there almost has to be a connection. Some connections are direct and obvious (genetic defects, internal organ malfunctions, etc), and some are indirect and less obvious (increased susceptibility to certain viral/bacterial/parasitic diseases, certain behavior traits that make them more likely to be exposed to danger than other chicks, etc). Even though statistics can be HIGHLY altered when using numbers less that 30, it is very unlikely that you would get a 100% fatality rate within 24 hours from genetic defects or shared congenital organ malfunctions. Typically those issues have high death rates in the first few days, up to 2-3 weeks, but then there is a wide range of lifespans in the survivors, depending on how severely the problem is impacting each animal. 100% fatality within 24 hours at 5 weeks of age doesn't fit that pattern. You're looking for something that has a very high death rate very quickly, but is selective based on either increased susceptiblity or increased exposure. Since all the chicks were in the same pen, but only the "Rudy chicks" were affected, any exposure differences would most likely be due to either behavior traits (more aggressive foraging dug up something dangerous, better flying ability took them somewhere the others couldn't reach, different taste tolerances made them accept or desire a toxic plant that the other chicks wouldn't eat, etc) or coincidence (the chicks were all socializing together in a clique when a small swarm of insects recently sprayed by poison flew into the pen, etc).
I hope you figure out what happened. Please let the rest of us know if you find out.
--April
