Estradiol concentration in the serum of the one-humped camel (Camelus dromedarius) during the various reproductive stages.

During the estrous cycle of the camel the concentration of estradiol (E2) varies between 9 and 110 pg/ml. In early estrus, the peak level of E2 (74.7 +/- 6.61 pg/ml, n = 11) is maintained for 2.9 +/- 1.83 days. The length of an estrous cycle is 17.2 days. In the 10th month of pregnancy the level of E2 rises abruptly to 338.3 +/- 162.42 pg/ml and continues to rise until the 12th month, peaking at 606 +/- 120.27 pg/ml. The hormone concentration then drops until the day of parturition (mean 113.4 +/- 26.51 pg/ml). The level of E2 during the nonbreeding season (May-November) is low (6-48 pg/ml).