Treatment with prostaglandin F2α and an intravaginal progesterone insert promotes follicular maturity in advance of gonadotropin-releasing hormone among postpartum beef cows,Theriogenology

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Treatment with prostaglandin F2α and an intravaginal progesterone insert promotes follicular maturity in advance of gonadotropin-releasing hormone among postpartum beef cows
Theriogenology ( IF 2.4 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.theriogenology.2020.08.018
R C Bonacker ₁ , K S Stoecklein ₂ , J W C Locke ₁ , J N Ketchum ₂ , E R Knickmeyer ₁ , C M Spinka ₃ , S E Poock ₄ , J M Thomas ₂

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An experiment was designed to evaluate treatments to promote ovarian follicular maturity in advance of administration of exogenous gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) for control of the bovine estrous cycle. We hypothesized prostaglandin F2α (PGF2α; 500 μg cloprostenol) followed by an intravaginal progesterone-releasing insert (CIDR; 1.38 g progesterone) would induce greater follicle size and serum estradiol at the time of GnRH administration. Postpartum cows (n = 194) in two locations were assigned to one of five treatments based on age, days postpartum, and body condition score. Cows in Treatment 1 were treated with the standard 7-d CO-Synch + CIDR protocol: administration of GnRH and CIDR insertion on Day -10, and administration of PGF2α and CIDR removal on Day -3. Treatments 2-5 were designed in a 2 × 2 factorial arrangement, with Treatment 1 included as an additional reference. On Day -17, cows in Treatments 2-5 received a CIDR insert, either with (Treatments 2 and 3) or without (Treatments 4 and 5) administration of PGF2α at CIDR insertion. On Day -10, all cows were administered GnRH, and CIDR inserts were either removed (Treatments 2 and 4) or remained in place until Day -3 (Treatments 3 and 5). Treatment with PGF2α and CIDR in advance of GnRH (Treatments 2 and 3) resulted in increased diameter of the largest ovarian follicle (P < 0.001) and increased serum concentrations of estradiol (P < 0.0005) on Day -10. In addition, variation among cows in CL status (no CL vs. a single CL vs. multiple CL) on Day -3 tended to be decreased (P = 0.08), with cows more likely to have a single CL rather than no CL or multiple CL. Lastly, the proportion of cows expressing estrus prior to fixed-time artificial insemination tended (P = 0.08) to be improved. Results support the hypothesis that administration of PGF2α and treatment with a CIDR for 7 days prior to GnRH promotes follicular maturity in advance of GnRH administration and may provide an approach by which to enhance response of postpartum beef cows to GnRH-based estrus synchronization programs.

中文翻译：

前列腺素 F2α 和阴道内黄体酮插入物治疗可在产后肉牛促性腺激素释放激素之前促进卵泡成熟

设计了一项实验来评估在施用外源性促性腺激素释放激素（GnRH；100 μg 促性腺激素）之前促进卵巢卵泡成熟的治疗，以控制牛的发情周期。我们假设前列腺素 F2α（PGF2α；500 μg 氯前列醇）和阴道内孕酮释放插入物（CIDR；1.38 g 孕酮）会在 GnRH 给药时诱导更大的卵泡大小和血清雌二醇。根据年龄、产后天数和身体状况评分，两个地点的产后奶牛 (n = 194) 被分配到五种治疗中的一种。治疗 1 中的奶牛用标准的 7 天 CO-Synch + CIDR 方案进行治疗：在第 -10 天施用 GnRH 和 CIDR，在第 -3 天施用 PGF2α 和去除 CIDR。处理 2-5 以 2 × 2 因子排列设计，处理 1 作为附加参考。在第 -17 天，处理 2-5 中的奶牛接受 CIDR 插入，在 CIDR 插入时有（处理 2 和 3）或没有（处理 4 和 5）施用 PGF2α。在第 -10 天，对所有奶牛施用 GnRH，移除 CIDR 插入物（治疗 2 和 4）或保持原位直到第 -3 天（治疗 3 和 5）。在 GnRH 之前用 PGF2α 和 CIDR 治疗（治疗 2 和 3）导致最大卵泡直径增加（P < 0.001）和第 -10 天雌二醇血清浓度增加（P < 0.0005）。此外，第 -3 天 CL 状态（无 CL 与单个 CL 与多个 CL）的奶牛之间的变化趋于减少（P = 0.08），奶牛更可能有单个 CL 而不是没有 CL 或多个 CL。最后，在固定时间人工授精前表达发情的奶牛比例趋于提高（P = 0.08）。结果支持这样的假设，即在 GnRH 之前施用 PGF2α 和用 CIDR 治疗 7 天可在 GnRH 施用之前促进卵泡成熟，并且可能提供一种方法来增强产后肉牛对基于 GnRH 的发情同步程序的反应。

更新日期：2020-11-01

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