Hillsddown, here is the second article and link from the cattle network
http://www.cattlenetwork.com/Baby_Calf_ ... tid=266634
Colostrum is the primary source of immediate natural protection. Ingestion of this antibody (immunoglobulin) rich milk is critical for newborn calf survival. The dam's serum antibodies (IgGs) are concentrated in the udder as colostrum during the last month of pregnancy. The concentration of antibodies is lower in heifers as compared to mature cows. For maximum protection, an adequate amount must be delivered within 4 to 12 hours of birth.
Colostrum in the beef cow tends to be more concentrated than in the dairy cow. Generally speaking, a 75-pound calf ingesting 2 to 3 quarts of its mother's milk in the first 12 hours after birth will receive adequate colostrum. But what can be done for the calf whose dam has no milk or is otherwise deprived of colostrum? The best substitute for the natural mother's colostrum is colostrum from another cow. This can be collected and kept frozen in quart containers. However, many modern freezers that have an automatic defrosting system may cause the frozen colostrum to lose a percentage of its protective antibodies when stored over a long period of time (e.g., 12 months).
Some care must be taken when thawing frozen colostrum. Studies have shown that rapid defrosting using boiling temperatures destroys a portion of the colostrum by destroying the protein antibodies. These same studies have shown that defrosting in a microwave at settings above 60 percent power has the same result. Two methods that can be recommended are: a warm water thaw where the container (1 or 2 quarts) of colostrum is immersed in 110°F water and stirred every 5 minutes to assure even thawing and warming (continue this process until colostrum reaches 104°F); or use of a microwave oven set at no more than 60 percent power. Again, agitate frequently to assure even warming and thawing, and stop when the colostrums reaches 104°F. Either process will take approximately 40 minutes.
We cannot assume that the antibody concentration in the colostrum of all cows or heifers is equal. In fact, studies have shown that the antibody concentration varies considerably from cow to cow, breed to breed, and heifer to heifer. There is no practical way to measure with certainty the antibody concentration of colostrums before delivery. Colostrometer measurements are helpful but may vary also. However, fresh or fresh-frozen and properly thawed colostrum is still the best source of natural protection for a newborn calf.
Source: Donald E Hansen, Extension Veterinarian, Oregon State University