کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2095981 1082146 2009 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of progesterone presynchronization and eCG on pregnancy rates to GnRH-based, timed-AI in beef cattle
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک علوم دامی و جانورشناسی
پیش نمایش صفحه اول مقاله
Effects of progesterone presynchronization and eCG on pregnancy rates to GnRH-based, timed-AI in beef cattle
چکیده انگلیسی

Three experiments were conducted to determine the effects of low-dose progesterone presynchronization and eCG on pregnancy rates to GnRH-based, timed-AI (TAI) in beef cattle (GnRH on Day 0, PGF2α on Day 7, with GnRH and TAI on Day 9, 54–56 h after PGF2α). Experiments 1 and 2 were 2 × 2 factorials with presynchronization (with or without a once-used CIDR; Days −15 to 0 in Experiment 1 and Days −7 to 0, with PGF2α at insertion, in Experiment 2), and with or without 400 IU eCG on Day 7 in suckled cows. In Experiment 3, suckled cows and nulliparous heifers were either presynchronized with a twice-used CIDR (Days −5 to 0) and PGF2α at insertion, or no treatment prior to insertion of a new CIDR (Days 0–7). Presynchronization increased (P < 0.05) ovulation rate to GnRH on Day 0 (75.0% vs 48.7%, 76.7% vs 55.0%, and 60.0% vs 36.1% for Experiments 1, 2, and 3, respectively), increased the diameter of the preovulatory follicle in Experiments 1 and 2, and increased the response to PGF2α (regardless of parity) in Experiment 1 (P < 0.01), and in primiparous cows in Experiment 2 (P < 0.01). Effects of presynchronization on pregnancy rates (53.4% vs 54.1%, 57.7% vs 45.3%, and 54.3% vs 44.4% for Experiments 1, 2, and 3, respectively) were influenced by parity and eCG (P < 0.05). Treatment with eCG had no effect (P > 0.05) on the diameter of the preovulatory follicle (Experiment 1), or the response to PGF2α (Experiments 1 and 2), but tended (P = 0.08) to improve pregnancy rates, especially in primiparous cows that were not presynchronized (P < 0.01). However, the effects of eCG and presynchronization were not additive.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Theriogenology - Volume 71, Issue 4, 1 March 2009, Pages 698–706
نویسندگان
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