Progesterone and Estrogen Levels in Peripheral Plasma of the Pregnant and Nonpregnant Roe Deer (Capreolus capreolus)

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Abstract
Progesterone (P) and estrogens (E) were determined in the pheripheral plasma of pregnant and nonpregnant roe deer with the beginning of the breeding season, (July) until time of expected parturition in May/June of the following year. (Exp. A). In nonpregnant animals, P (mean ng/ml ± SEM) increased from 0.12 ± 0.02 in July to 1.69 ± 0.36 in August. From August through March, mean values ranged between 1.93 ± 0.61 and 3.00 ± 0.65, followed by a decrease in April (1.09 ± 0.39) with basal levels reached in May (0.1 ± 0.04). In the pregnant animals, P similarly started to rise in July to a first peak (3.55 ± 0.48) in August; values thereafter were between 2.08 ± 0.19 and 2.80 ± 0.27 until December. A second increase up to 4.81 ± 0.68 in January was observed in pregnant animals, which was of different magnitude from the nonpregnant animals. A gradual decrease from 4.45 ± 0.57 to 1.01 ± 0.44 occurred from March to May. Concentrations of E (mean pg/ml ± SEM) varied between 57 ± 7 and 107 ± 27 in the nonpregnant animals and were higher in the pregnant animals during the last 6 months of gestation. In a more intensive study of 2 nonpregnant animals (Exp. B), P exhibited a short elevation at the end of July and the beginning of August, followed by a continuous increase throughout the period examined (October). It is concluded that the corpus luteum remains active once it has formed, even in the nonpregnant animal, during the greater portion of the reproductive period. The data obtained also suggest that in the pregnant animal, placental P and E production commences at the time of placental attachment in January.