Serum progesterone profiles during the estrous cycle of dairy and beef cows determined using immunochemiluminescence (CLIA) and validated using enzyme-linked immunosorbent assay (ELISA)

Abstract

This study aimed to validate the methodology of immunochemiluminescence (CLIA) using an enzyme-linked immunosorbent assay (ELISA) to determine serum progesterone (P4) concentrations in non-pregnant multiparous dairy (12 Holstein cows) and beef (18 Nellore cows) cows during the estrous cycle. Cows with corpus luteum were chosen for estrus and ovulation synchronization by administering 500 mcg of cloprostenol. After luteolytic application, the animals were subjected to ovarian ultrasonography (US) daily to verify ovulation (day zero of the cycle) and two blood samples were collected for P4 determination using CLIA and ELISA. Samples were centrifuged to obtain serum and frozen at -20 °C for later measurement. ELISA and CLIA values were compared using the paired t-test, regression, analysis of variance, and coefficient of determination (R2) to verify sensitivity and linear correspondence. The P4 concentration determined by both methodologies showed a similar profile; the P4 profiles were higher in beef cattle than in dairy cattle. The correspondence between the methodologies resulted in a high quotient for R2 the P4 profiles. It was concluded that CLIA can be used for hormonal determinations of bovine serum P4. CLIA showed a high linear correspondence with ELISA values and can thus aid reproductive biotechnologies for hormone determination.