"Ours is the ONLY Independently “Tested & Certified” 6-hour Colostrum! Tested and Certified by Dr. Don Lein, Professor Emeritus, Cornell University! Natural vs. Synthetic for Higher Bioavailability Natural Chymosin, known also as rennin, is a proteolytic enzyme. Its role is to bypass stomach acids and provide a higher absorption rate. Natural is ALWAYS better than a synthetic!"