Hormone analyses. Serum samples were analyzed by RIA for concentrations of LH, FSH, estradiol, and progesterone. Earlier studies in our laboratory (unpublished) showed that the antiserum to progesterone did not cross-react with MAP which permitted the measurement of endogenous progesterone in MAP-treated ewes. Concentrations of LH and FSH are given in terms of NIAMDD-oLH-24 and NIAMDD-oFSH-1, respectively. The sensitivities of assays were as follows: 0.10 ng/ ml (LH and FSH), 1.0 pg/ml (estradiol), and 0.03 ng/ml (progesterone). The range of standard curves was from 0.06 to 8.0 ng/ml, 0.12 to 16.0 ng/ml, 1.0 to 50 pg/ml, and 0.1 to 10 ng/ml, in the LH, FSH, estradiol, and progesterone assays, respectively.
All LH analyses were conducted in a single assay; the intraassay coefficients of variation (CVs) for mean LH concentration of 0.19 or 0.97 ng/ml were 12.3% or 8.9%, respectively.
For FSH, the intraassay and interassay CVs were 6.4% and 2.9% or 7.1% and 5.9%, for reference sera with mean concentrations of 1.28 or 2.41 ng/ ml, respectively. The intraassay and interassay CVs for estradiol were 14.0% and 12.2%, or 10.3% and 7.2%, for reference sera with mean concentrations of 5.1 or 13.9 pg/ml, respectively. Intraassay and interassay CVs for reference sera with mean progesterone concentrations of 0.29 or 0.69 ng/ml were 13.2% and 9.4% or 18.5% and 7.3%, respectively.