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

ABSTRACT. 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 4th and 5th 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.

摘要。本研究旨在从内分泌学与行为学层面，对母羊的生殖周期进行表征。本研究通过酶免疫测定（Enzyme Immunoassay，EIA）检测血样中的孕酮（progesterone，P4），并通过放射免疫测定（Radioimmunoassay，RIA）检测雌二醇（estradiol），以明确土耳其安纳托利亚中部（北纬39.57°，西经32.53°）地区的11只非妊娠与9只妊娠怀特卡拉曼绵羊（White Karaman）的全年繁殖策略。发情周期与发情持续时长分别为18.36±1.03天和35.16±5.95小时。根据激素与行为学数据显示，繁殖季时长分别为283±63.36天和229.64±63.74天（p<0.01）。发情发生频率的峰值与谷值分别出现在10月和6-7月。全年孕酮水平范围为0.01~9.0 ng·mL⁻¹，乏情期孕酮水平范围为0.01~0.16 ng·mL⁻¹。发情周期内血浆雌二醇平均水平为8.42±2.51 pg·mL⁻¹。根据行为观察与激素检测数据，产后乏情期时长分别为134.8±18.5天和120.78±29.89天（n=9）。妊娠期第1至5个月的孕酮浓度范围为4.54~15.08 ng·mL⁻¹。妊娠期第4、5个月的孕酮水平显著高于其余月份（p<0.01）。怀特卡拉曼绵羊的生殖活动以繁殖季较长为特征，其对光周期刺激的相对不敏感性可实现高效的反季节羔羊生产。