The effectiveness of colostrum-replacement products can be quite variable, even when fed to deliver the same amount of immunoglobulins. Why is that?

“There is a significant difference in how well the antibodies in different products are absorbed,” notes Geof Smith, veterinarian at North CarolinaStateUniversity.

A side-by-side product comparison, reported in the October 2006 Journal of the American Veterinary Medical Association, shows just how true that is. In the study, 81 percent of calves fed a commercial colostrum replacer containing 100 grams of immunoglobulin G achieved adequate passive transfer. However, only 10 percent of calves fed a different commercial product with an equivalent amount of IgG achieved adequate passive transfer.

Both products were derived from maternal colostrum.

Product B shown in the table below could be considered an alternative to colostrum in dairy calves, say the researchers, but Product A failed to routinely provide adequate serum IgG concentrations. The results shown below also reiterate the importance of evaluating colostrum replacers for effectiveness prior to feeding them.


Average serum IgG

Average serum
total protein

Percent with adequate passive transfer1

Group 1:
4 quarts fresh colostrum
(Average IgG concentration of 448 grams)







Group 2:
Two packages of Product A
(Equivalent to 100 grams of IgG)







Group 3:
One package of Product B
(Equivalent to 100 grams of IgG)







Group 4:
Two packages of Product B
(Equivalent to 200 grams of IgG)








1Adequate passive transfer was defined as a serum IgG concentration greater than 1,000 mg per deciliter.

Source: Oct. 15, 2006 Journal of the American Veterinary Medical Association, page 1282-1285.