Waiting 12 hours to harvest colostrum from a fresh cow reduces the antibody count by half, says Don Gardner, veterinarian in Huddleston, Va. That’s because as the cow produces more milk, the extra milk dilutes the initial IgG-rich colostrum. So, even though the cow produces more total colostrum, you will have to feed twice as much to get the same amount of antibodies into the calf as you would if you had harvested the colostrum shortly after calving.