Bovine salivary progesterone: Application to the assessment of ovarian function and early pregnancy diagnosis

Abstract

A simple, sensitive and reproducible direct RIA method for the determination of low quantities of progesterone in bovine saliva was developed and applied for the assessment of the ovarian function and early pregnancy diagnosis in cows and heifers. The sensitivity of the method was 3.3±0.9 pg/tube, intra- and interassay CVs for low and high pools of saliva were 4.7 and 3.8% and 14.6 and 10.7%, respectively, and the mean recoveries when 200 μl of stripped saliva were supplemented with 20, 50, 100, 300 pg standard progesterone were 93.1, 94.0, 101.8 and 100.9%. The ovarian function was assessed in matched blood and saliva samples from pregnant and early postpartum cows. It was found that salivary levels measured by this method reflected the changes in plasma progesterone concentrations. The saliva/plasma progesterone ratio × 100 during the follicular phase was 15% while during the luteal phase it was 12%. The salivary progesterone content was used to diagnose pregnancy in cows 21 days after service. The accuracy of the method was 100% for the negative and 73.7% for the positive cases.