Enzyme-immunoassay for determination of progesterone in milk from cows

Abstract
An enzyme-immunoassay using horseradish peroxidase as label is described. The assay has a sensitivity of 0.1-20 pmol, i.e., 0.03-0.63 ng and intra- and interassay coefficients of variation of < 10% when used for the determination of progesterone in samples of milk from cows. Comparison with a radioimmunoassay based on [3H] tracer showed excellent correlation (r = 0.98) for milk samples from cows during estrous cycle and early pregnancy.