When I first started with quail, I had a couple cases of wry neck. Nothing scientific, just opinions from the wonderful world of BYC. Since that time and feeding the same Purina Game Bird and Turkey Starter, I've used Rooster Booster and a probiotic blend with niacin and haven't had wry neck issues. I am a small hatcher and this observation/opinion is worth what you paid for it.It’s good to know I have a few options now.
@RUNuts Purina does state that niacin is included in its starter feed. Have you determined it is deficient in niacin which is why you supplement?
Beyond incidental evidence, I can prove nothing. Like a couple people mentioned, it couldn't hurt.
During some other discussions on quail health and maybe in this thread, there were some scientific papers referenced that pointed that quail needed increased amounts of niacin for health over other birds. Others may be able to post a link. Another opinion was that niacin degraded in the feed faster than other nutrients. I like avoiding wry neck.