Reproductive cycles in white Karaman ewes: comparison of ovarian hormone secretion and reproductive behavior in non-pregnant and pregnant ewes in semi-intensive conditions

Resumo

The objective of this study was to characterize the reproductive cycle both endocrinologically and behaviorally in ewes. Blood samples were analyzed by EIA for progesterone (P₄), and RIA for estradiol in order to determine the breeding strategy of non-pregnant (n = 11) and pregnant (n = 9) White Karaman throughout the year in the Middle Anatolia (39.57⁰N, 32.53⁰W), Turkey. Estrous cycle lengths and estrous lengths were 18.36 ± 1.03 days and 35.16 ± 5.95 hours, respectively. The breeding season durations were 283 ± 63.36 days and 229.64 ± 63.74 days according to hormonal and behavioral data respectively (p £ 0.01). The highest and lowest data of estrous occurrence frequency was observed in October and June-July, respectively. P₄ levels ranged from 0.01 to 9.0 ng mL^-1 throughout the year and from 0.01 to 0.16 ng mL^-1 during anestrous. Mean plasma estradiol levels were 8.42 ± 2.51 pg mL^-1 during the estrous cycle. Postpartum anestrous durations were 134.8 ± 18.5 and 120.78 ± 29.89 days (n = 9) according to behavioral observation and hormonal data, respectively. P₄ concentration for the months 1 – 5 of the gestation period ranged from 4.54 to 15.08 ng mL^-1. P₄ concentrations in 4^th and 5^th months of gestation were higher than the other months (p £ 0.01). White Karaman reproductive activity is characterized by an extended breeding season and their relatively insensitivity to photoperiod stimulation allows for efficient out of season lamb production.