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SUMMARY
A survey has been made of the steroids in cows' milk using a method for the group analysis of steroids. Serial studies during and after pregnancy showed changes in progesterone concentration consistent with known variations in plasma concentrations. More progesterone was obtained from samples taken at the later stages of milking and samples obtained in the evening generally contained more progesterone than morning samples. Steroids were concentrated in the cream.
Relatively constant levels of 5α-androstane-3,17-dione were found and it is suggested that this steroid is of adrenal origin. The predominance of 5α steroids in milk suggests that these are derived, at least in part, from metabolism in the mammary gland. The possible use of these findings in diagnosis of pregnancy and in studies of the hormonal control of lactogenesis is indicated.
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The purpose of this report is to present evidence obtained by gas chromatography combined with mass spectroscopy that pregn-4-ene-3,20-dione (progesterone) can be obtained from cows' milk during pregnancy.
A method has been developed for the estimation of 17- and 20-oxogenic steroids in milk. It consists of an initial saponification by boiling 50 ml samples of milk diluted with an equal volume of water for 1 h with 10 g potassium hydroxide followed by gentle mechanical extraction with diethyl ether. The non-saponifiable lipids are then oxidized with 7·5% (w/v) CrO3 in 50% aqueous acetic acid. A Girard separation of the oxidation products is used to obtain a ketonic fraction which is chromatographed using chloroform (A.R.) on thin layers of silica gel. The areas corresponding to steroid ketones are eluted and the extracts subjected to gas chromatography on a QF-1 coated column.
In addition to measuring progesterone, this procedure would convert
