Tandem Administration of Prostaglandin F and Gonadotropin-Releasing Hormone in Beef Heifers and Cows as a Convergent Presynchronization Method in the 7 & 7 Synch Protocol.

IF 2.7 2区 农林科学 Q1 AGRICULTURE, DAIRY & ANIMAL SCIENCE
Animals Pub Date : 2025-05-05 DOI:10.3390/ani15091329
Lucas J Palcheff, Genevieve M VanWye, Kimberly R Ricardo, Kendal L Green, Franklin J Even, Samantha R Roberts, Adella B Lonas, Christine M Spinka, Scott E Poock, Saulo Menegatti Zoca, Jessica N Drum, Jordan M Thomas
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Abstract

An experiment was designed to evaluate modifications to the 7 & 7 Synch protocol, with the hypothesis that tandem administration of prostaglandin F2α (PG) and gonadotropin-releasing hormone (GnRH) during the presynchronization portion of the protocol would generate a convergent ovarian response among anestrous and estrous cycling females. Nulliparous, primiparous, and multiparous Angus and Angus-cross females were blocked based on parity and pre-treatment luteal status and, within a block, randomly assigned to one of three treatments. The females assigned to the 7 & 7 Synch treatment (n = 765) received an intravaginal progesterone-releasing insert (CIDR®) and an administration of PG on Day 0, GnRH on Day 7, and PG concurrent with CIDR removal on Day 14. Estrotect™ estrus detection aids were applied on Day 14 at the time of CIDR removal and PG administration. The females assigned to the 7 & 7 + G treatment (n = 769) received the same treatment schedule, with the modification that GnRH was administered in tandem with PG on Day 0. The females assigned to the 7 & 7 + G + P treatment (n = 786) received the same treatment schedule, with the modification that GnRH was administered in tandem with PG on both Days 0 and 7. Fixed-time artificial insemination (FTAI) was performed at 54 ± 2 h (nulliparous) or 66 ± 2 h (primiparous and multiparous) after CIDR removal. Transrectal ovarian ultrasonography was performed on Days 7 and 14 to characterize the largest follicle diameter (LFD) and the presence of corpora lutea (CL). Estrus prior to FTAI was characterized using estrus detection aids. Pregnancy status was determined via transrectal ultrasonography approximately 60-100 days after FTAI. The proportion of multiparous females with CL on Day 14 tended to be greater following treatment with 7 & 7 Synch or 7 & 7 + G (90% and 87%, respectively), as compared to females treated with 7 & 7 + G + P (82%; p = 0.09). A greater proportion of multiparous females expressed behavioral estrus prior to FTAI when treated with 7 & 7 + G + P (90%) as compared to multiparous females treated with 7 & 7 + G (79%; p < 0.002) or 7 & 7 Synch (78%; p = 0.0004); however, pregnancy rates resulting from FTAI did not differ based on treatment. In summary, tandem administration of GnRH and PG on Days 0 and 7 of the 7 & 7 Synch protocol effectively generated a convergent ovarian response among females with variable pretreatment luteal status but failed to enhance pregnancy rates to FTAI.

7 & 7同步方案中前列腺素F2α和促性腺激素释放激素在肉牛和小母牛中串联应用的收敛预同步方法
我们设计了一项实验来评估7 & 7同步方案的修改,假设在方案的同步前部分串联给药前列腺素F2α (PG)和促性腺激素释放激素(GnRH)会在处于停经期和发情期的雌性中产生趋同的卵巢反应。根据胎次和治疗前黄体状态,将未产、初产、多产的安格斯和安格斯杂交雌鼠隔离,并在一个区域内随机分配到三种治疗方法中的一种。被分配到7和7同步治疗组的女性(n = 765)在第0天接受阴道内孕激素释放剂(CIDR®)和PG的治疗,在第7天接受GnRH,在第14天接受PG同时去除CIDR。在第14天去除CIDR和给药PG时应用Estrotect™发情检测助剂。分配到7和7 + G组的女性(n = 769)接受相同的治疗计划,修改为在第0天GnRH与PG同时施用。分配到7和7 + G + P治疗组的女性(n = 786)接受相同的治疗计划,修改为GnRH与PG在第0天和第7天同时施用。取下CIDR后,分别在54±2小时(无产)或66±2小时(初产和多产)进行定时人工授精(FTAI)。在第7天和第14天进行经直肠卵巢超声检查,以确定最大卵泡直径(LFD)和黄体(CL)的存在。使用发情检测辅助工具对FTAI前的发情进行表征。FTAI后约60-100天通过经直肠超声检查确定妊娠状况。与7和7 + G + P组相比,7和7同步组或7和7 + G组在第14天发生CL的多产雌鼠比例(分别为90%和87%)更大(82%;P = 0.09)。与7 & 7 + G治疗的多产雌性相比,7 & 7 + G + P治疗的多产雌性在FTAI前表现出行为性发情的比例(90%)更高(79%);p < 0.002)或7 & 7 Synch (78%;P = 0.0004);然而,FTAI导致的妊娠率并没有因治疗而不同。综上所述,在7 & 7同步方案的第0天和第7天,GnRH和PG的串联给药有效地在不同黄体状态的女性中产生了趋同的卵巢反应,但未能提高FTAI的妊娠率。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Animals
Animals Agricultural and Biological Sciences-Animal Science and Zoology
CiteScore
4.90
自引率
16.70%
发文量
3015
审稿时长
20.52 days
期刊介绍: Animals (ISSN 2076-2615) is an international and interdisciplinary scholarly open access journal. It publishes original research articles, reviews, communications, and short notes that are relevant to any field of study that involves animals, including zoology, ethnozoology, animal science, animal ethics and animal welfare. However, preference will be given to those articles that provide an understanding of animals within a larger context (i.e., the animals'' interactions with the outside world, including humans). There is no restriction on the length of the papers. Our aim is to encourage scientists to publish their experimental and theoretical research in as much detail as possible. Full experimental details and/or method of study, must be provided for research articles. Articles submitted that involve subjecting animals to unnecessary pain or suffering will not be accepted, and all articles must be submitted with the necessary ethical approval (please refer to the Ethical Guidelines for more information).
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