He's also supplemented with a loose mineral/salt mix so that should cover any deficiencies, I also use Source micronutrients, and he has free access to block minerals/salt.
Biotin...been looking into that one. The feeds I have access to locally don't have it included, so I will have to supplement. I only just started changing his feeding plan and researching the feed requirements for the long distance riding equine. Lots to read and learn :) and many opinions as well. We all do the best we can :)