Tandem Administration of Prostaglandin F2α 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
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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引用次数: 0
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.
AnimalsAgricultural 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).