Plasma Estradiol in Holstein and Beef Cows During the Periparturient Period

Abstract

Plasma estradiol, measured by radio-immunoassay, was compared in Holstein and beef cows during the periparturient period. A disposable Celite column was used for separation of estrogens. The antibody-estrogen complex was separated by charcoal and centrifugation. Circulating plasma estradiol was higher in 11 Holstein than in 9 beef cows prior to parturition. For Holstein cows, among nonsignificant differences, highest mean concentrations were 580 pg/ml on the day before parturition and 440 pg/ml on the day of parturition. Beef cows reached a peak of 538 pg/ml on the day of parturition. Concentrations rapidly and similarly decreased in both groups following parturition. © 1974, American Dairy Science Association. All rights reserved.