A method of scoring the biological activity of bioactive agents like colostrum comprising conducting separate bioassays for cell restitution and cell proliferation on the bioactive agent, a comparative growth factor stimulating agent, and (preferably) a negative baseline control sample containing the cells and growth medium alone. These values are then plugged into the equations provided in this application to calculate a Restitution Score ("RS"), Proliferation Score ("PS"), and a composite repair and protection factor score ("RPF"). In this manner, the bioactivity of compositions that enhance the repair and/or proliferation of mammalian cells, or act as additives to growth media used to maintain and grow laboratory cell cultures can be quickly and reproducibly obtained. This invention may be applied to a wide variety of bioactive agents used to treat a large assortment of functional cells in organ tissues.