I hadn't noticed it before you posted about it, but it is really interesting. I wonder if it is because not specifying allows manufacturers to choose the cheapest/most available pre-mix at any given moment?
I did find this short article and wonder if some of the ideas mentioned in it are part of the issue as well:
https://www.wattagnet.com/blogs/13-...niversal-broiler-vitamin-trace-mineral-premix
I doubt that there would be a response but it would be interesting to send an email to the author of the article and ask why poultry feed manufacturers are so cagey on the subject.
Also - I want to join the chorus of people saying thank you for putting this information together.