Transfer factor factors are contraindicated for women who are pregnant or breastfeeding. When human- and bovine-derived transfer factor are generated from blood cells they carry the potential for blood-borne disease such as HIV/AIDS and Hepatitis C. Colostrum is a form of milk produced by the mammary glands of mammals (including humans) in late pregnancy. Colostrum also contains multiple immune modulating molecules, including high antibody levels. Based on studies noting an overlap in the observed in vitro effects between a molecule contained in colostrum called colostrinin and the dialyzable leukocyte extract mentioned above, a hypothesis formed that the two were the same. There
Colostrum studies indicate that colostrum should be fed to bovines within the first thirty minutes to maximize IgG absorption rates. Colostrum varies in quality and quantity. In the dairy industry, the quality of colostrum is measured as the amount of IgG (Immunoglobulin G) per liter. It is recommended that newborn calves receive at least 4 quarts (liters) of colostrum with each containing at least 50 grams of IgG/liter. Testing of colostral quality can be done by multitude of devices including colostrometer, optical refractometer or digital refractometer. Mature dairy cattle produce an average of 33 liters of colostrum in the first milking