The oestrogenic activity of bovine colostrum.

The oestrogenic activity of human colostrum (Lacassagne & Nyka, 1934) and the undoubted importance of colostrum for the neo-natal calf led us to test bovine colostrum for oestrogenic activity. Oestrogens found in animal tissues and body fluids during the past 23 years, in particular those in pregnant-cow bile (Pearlman, Rakoff, Cantarow & Paschkis, 1947), have always been phenolic in chemical nature, although occurring partly as water-soluble, ether-insoluble derivatives (conjugates) in the case of some urines (Cohen, Marrian & Odell, 1936; Schachter & Marrian, 1938). We therefore assumed that oestrogens in colostrum would occur either as the free phenols or as derivatives yielding the phenols on acid hydrolysis; and in either case be extractable by boiling methanol.