There is no requirement for biotin established for the horse because the microbial population of the gastrointestinal tract is thought to produce adequate amounts. With that said, using a therapeutic amount of biotin has a positive effect on hoof integrity in some horses. The research studies that have shown positive results on hoof quality with biotin supplementation used 15-20 mg biotin per day. Most hoof supplements on the market offer 6-30 mg per day. Because you are not buying the biotin in a commercial supplement, I would recommend making sure the biotin you have is d-biotin, which is the only active isomer.  Also, biotin has a fairly short shelf life and should be used within six months of purchase. I do not know the concentration of the product you have, but if it is on the label, try to figure out how much would provide 15 or 20 mg per day.