کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2073367 1544767 2011 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Patterns of estrous cycles, estrous behavior, and circulating prolactin in spring and summer in ewes selected for autumn lambing and exposed to ambient or long-day photoperiods
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک علوم دامی و جانورشناسی
پیش نمایش صفحه اول مقاله
Patterns of estrous cycles, estrous behavior, and circulating prolactin in spring and summer in ewes selected for autumn lambing and exposed to ambient or long-day photoperiods
چکیده انگلیسی
Estrous behavior in response to ambient and long-day photoperiods was evaluated in ewes developed by 10 years of selection for ability to lamb in autumn. Following October lambing, 67 ewes were moved indoors and exposed to long-day (16L:8D) or ambient photoperiods from February 2 until July 6. Two vasectomized rams with marking harnesses were housed with each group. Estrous behavior was monitored twice weekly. Ewes from the selection line were unresponsive to long days, with no effects on estrous behavior, frequency of ovulation, or circulating prolactin. Adult ewes were anestrus for only 34 ± 3 d, but 2- and 3-years-old ewes were anestrus for 72 ± 7 and 57 ± 10 d, respectively. Frequencies of ovulation based on circulating progesterone concentrations in March, May, and June were 97%, 95% and 52%, respectively, indicating that many ewes that did not exhibit estrus still ovulated. Prolactin concentrations increased from 10 ng/ml in February to 27 ng/ml in March and 173 ng/ml in June but were not affected by light treatment. Ten ewes that failed to exhibit estrus behavior for at most 24 d during the main study were then monitored for 74 additional long days. Nine of 10 ewes did not exhibit estrus for periods similar to 1 or 2 estrus cycles during this period, but eight ewes re-initiated cycles by the end of the study on September 18. Selection for ability to lamb in autumn thus resulted in ewes with an abbreviated seasonal anestrus and reduced sensitivity to long days.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Animal Reproduction Science - Volume 129, Issues 1–2, November 2011, Pages 30-36
نویسندگان
, , ,