Samir Burato , Madison Blake Walker , Lucas Melo Goncalves , Nicola Oosthuizen , Saulo Menegatti Zoca , Darren Dwayne Henry , Francine Messias Ciriaco , Juliana Ranches , Pedro Levy Piza Fontes
{"title":"Influence of early progesterone removal on follicular development, expression of estrus, and pregnancy rates in presynchronized postpartum beef cows","authors":"Samir Burato , Madison Blake Walker , Lucas Melo Goncalves , Nicola Oosthuizen , Saulo Menegatti Zoca , Darren Dwayne Henry , Francine Messias Ciriaco , Juliana Ranches , Pedro Levy Piza Fontes","doi":"10.1016/j.anireprosci.2024.107541","DOIUrl":null,"url":null,"abstract":"<div><p>The objective of this study was to evaluate the impact of early progesterone removal on pregnancy rates to fixed-time artificial insemination (FTAI) in presynchronized beef cows. Postpartum beef cows (<em>n</em> = 882) were randomly assigned to 1 of 2 treatments: 1) <strong>7&7 Synch</strong>: cows received a controlled internal drug release insert (CIDR) and a 25-mg injection of prostaglandin F<sub>2α</sub> on day 0, 100 μg of GnRH on day 7, a second injection of prostaglandin F<sub>2α</sub> (PG2) at CIDR removal on day 14, and a second injection of GnRH at FTAI 60–66 h after PG2 (day 17); 2) <strong>7&6 Synch</strong>: cows received the same treatment as 7&7 Synch; however, CIDR removal occurred in conjunction with PG2 on day 13, while FTAI remained at 60–66 h after CIDR removal (day 16). Ovarian ultrasonography was performed to determine follicle diameter at PG2 and FTAI in a subset of cows (<em>n</em> = 40). Cows exposed to the 7&7 Synch tended to have larger follicle diameter at PG2 compared with 7&6 Synch cows (<em>P</em> = 0.09); however, there were no differences in follicle diameter at FTAI. No differences were determined between treatments for the expression of estrus (7&7 Synch: 61.6 ± 5.30; 7&6 Synch: 54.1 ± 5.45; <em>P</em> = 0.31) or pregnancy rates to FTAI (7&7 Synch: 60.8 ± 3.83; 7&6 Synch: 57.0 ± 3.84; <em>P</em> = 0.42). In conclusion, early removal of progesterone did not impact pregnancy rates in presynchronized beef cows.</p></div>","PeriodicalId":7880,"journal":{"name":"Animal Reproduction Science","volume":null,"pages":null},"PeriodicalIF":2.2000,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Animal Reproduction Science","FirstCategoryId":"97","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0378432024001325","RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"AGRICULTURE, DAIRY & ANIMAL SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
The objective of this study was to evaluate the impact of early progesterone removal on pregnancy rates to fixed-time artificial insemination (FTAI) in presynchronized beef cows. Postpartum beef cows (n = 882) were randomly assigned to 1 of 2 treatments: 1) 7&7 Synch: cows received a controlled internal drug release insert (CIDR) and a 25-mg injection of prostaglandin F2α on day 0, 100 μg of GnRH on day 7, a second injection of prostaglandin F2α (PG2) at CIDR removal on day 14, and a second injection of GnRH at FTAI 60–66 h after PG2 (day 17); 2) 7&6 Synch: cows received the same treatment as 7&7 Synch; however, CIDR removal occurred in conjunction with PG2 on day 13, while FTAI remained at 60–66 h after CIDR removal (day 16). Ovarian ultrasonography was performed to determine follicle diameter at PG2 and FTAI in a subset of cows (n = 40). Cows exposed to the 7&7 Synch tended to have larger follicle diameter at PG2 compared with 7&6 Synch cows (P = 0.09); however, there were no differences in follicle diameter at FTAI. No differences were determined between treatments for the expression of estrus (7&7 Synch: 61.6 ± 5.30; 7&6 Synch: 54.1 ± 5.45; P = 0.31) or pregnancy rates to FTAI (7&7 Synch: 60.8 ± 3.83; 7&6 Synch: 57.0 ± 3.84; P = 0.42). In conclusion, early removal of progesterone did not impact pregnancy rates in presynchronized beef cows.
期刊介绍：
Animal Reproduction Science publishes results from studies relating to reproduction and fertility in animals. This includes both fundamental research and applied studies, including management practices that increase our understanding of the biology and manipulation of reproduction. Manuscripts should go into depth in the mechanisms involved in the research reported, rather than a give a mere description of findings. The focus is on animals that are useful to humans including food- and fibre-producing; companion/recreational; captive; and endangered species including zoo animals, but excluding laboratory animals unless the results of the study provide new information that impacts the basic understanding of the biology or manipulation of reproduction.
The journal''s scope includes the study of reproductive physiology and endocrinology, reproductive cycles, natural and artificial control of reproduction, preservation and use of gametes and embryos, pregnancy and parturition, infertility and sterility, diagnostic and therapeutic techniques.
The Editorial Board of Animal Reproduction Science has decided not to publish papers in which there is an exclusive examination of the in vitro development of oocytes and embryos; however, there will be consideration of papers that include in vitro studies where the source of the oocytes and/or development of the embryos beyond the blastocyst stage is part of the experimental design.
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