I get mine from a local outfit that mixes their own. We were having the same issue until we started adding some scraps to their feed. Moving to chick starter seems to have helped as well. To me it doesn't look like a brand issue and more of an issue with a base supplier of the ingredients. Perhaps letting the grain get too old or harvesting at the wrong time is causing nutritional deficiencies. I don't have the money to send any to a lab but, it'd be nice to see the results if someone did.