There is no known affects of too much biotin. It is a water solulable vitamin. Your horse can have not enough biotin, but there is no history of problems caused by an overdose of boitin.
A good way...
When it's close to " nothing " I'd say less than 10%. In a survey taken by USA Today several years ago, the most popular answers for this very question was " about 3 % " and " very little ". 10 % is...
