While I'm not a mead maker, I'd recommend you check out Moonlight Meadery's Michael Fairbrother episodes on the Session ... seemed like a wealth of information regarding yeast maintenance and heath and quite a bit on nutrients as I recall. Pretty sure he covered rates. He started doing some sponsored spots where he gave out tips, I think 2014 to 2015 and he was on first in early May 2012.
If you don't want to have to suffer though the
for info he was also on Brad Smith's podcast,
http://beersmith.com/blog/2012/07/26/mo ... odcast-43/ .
Geezer_brew