Analysis of progesterone and estrone-sulfate in feces of American Bison using liquid chromatography coupled to mass spectrometry: Technical validation and correlation with blood levels.

American Bison's wild nature limits blood sample availability to study its endocrinology. This report describes progesterone (P4) and estrone-sulfate (E1S) assays in American Bison feces using Liquid Chromatography coupled with Mass Spectrometry (LC-MS). In 2 ranches, samples of feces (n = 73) and serum (n = 93) were collected in pregnant and nonpregnant American Bison.