Radioimmunoassay Technique for Measuring Cortisol in Milk

Abstract

A sensitive radioimmunoassay procedure for measurement of cortisol was developed for use in whole or skim milk. Cortisol concentrations were similar in whole and skim milk indicating that this steroid is not associated with milk lipids. The use of skim milk provides a faster and simplified approach to the study of cortisol in milk. Mean and standard errors of cortisol concentrations in skim milk samples collected at 24:00 and 12:00 h from 7 cows for 1 wk were 0.71 .+-. 0.05 and 0.69 .+-. 0.07 ng/ml. Cortisol in colostrum averaged 1.59 .+-. 0.07 ng/ml. [Milk samples may offer a simple means for monitoring adrenal activity in large numbers of lactating cows in a variety of situations.].