Uterine Involution, Follicle Development and Concentrations of Plasma Progesterone, 20α-OH-Progesterone and Total Estrogen Levels During the Postpartum Period in Anatolian Donkeys

In this study, it is aimed to determine the length of estrus cycle, size of the preovulatory follicle, and ovulation time during the postpartum period (pp) in Anatolian jennies and to measure steroid hormone levels during the same period. Five healthy Jennies at late-stage of gestation were included in the study. During the post partum period, plasma progesterone (P4), total estrogen (E2) and 20α-OH-progesterone (20α-OH-P4) levels were studied by RIA. Ovarian activity and uterus involution were determined by rectal palpation and ultrasound examinations. The first postpartum behavioral estrus occurred as early as 6 days pp. Follicles were reached to a preovulatoric size of 30 to 35 mm during the 2nd day of estrus, during which plasma P4, E2 and 20α-OH-P4 concentrations were 0.9±0.40 ng/ml, 6.82±4.64 ng/ml and 0.98±0.21 ng/ml, respectively. The first ovulation occurred 10-15 days after parturition. During the first postpartum cycle, plasma P4 reached to a maximum concentration 14 days after ovulation. The second estrus was observed 32.2±1.58 days postpartum period (pp). The estrus behaviour lasted 6.0±1.00 days and 5.6±1.67 days in the first and second cycles, respectively. The uterus borders were detected by rectal palpation as early as 3 and 4 days postpartum period (pp). The uterus was totally palpable 6-9 days after parturition. Importantly, a high correlation was determined between the P4 and 20α-OH-P4 concentrations.