There is no disrespect to you, but since I try to help others here with dosages and treatments, I have looked up dosages in as many poultry drug references or studies that I can find. Since most chicken feed already contains enough vitamin E and selenium already, only small amounts are needed for neurological conditions such as wry neck. I only have about 12 years of experience, but others here tend to use those same dosages. I’m glad that you have had good results with your flocks for so many years. Unfortunately, there are not a lot of good sources available for drug dosages. Plumbs Veterinary Drug Book is a good one. On this forum, most of us try to suggest treatments we have tried or know to be correct, and it is up to the person asking for help to read all of the replies and choose for themselves what to do.