{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:14:36Z","timestamp":1760058876898,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,5,5]],"date-time":"2025-05-05T00:00:00Z","timestamp":1746403200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000199","name":"United States Department of Agriculture (USDA), National Institute of Food and Agriculture (NIFA)","doi-asserted-by":"publisher","award":["2022-68008-36646"],"award-info":[{"award-number":["2022-68008-36646"]}],"id":[{"id":"10.13039\/100000199","id-type":"DOI","asserted-by":"publisher"}]},{"name":"USDA North-Central 1201 Multi-State Project","award":["2022-68008-36646"],"award-info":[{"award-number":["2022-68008-36646"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>An experiment was designed to evaluate modifications to the 7 &amp; 7 Synch protocol, with the hypothesis that tandem administration of prostaglandin F2\u03b1 (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 &amp; 7 Synch treatment (n = 765) received an intravaginal progesterone-releasing insert (CIDR\u00ae) and an administration of PG on Day 0, GnRH on Day 7, and PG concurrent with CIDR removal on Day 14. Estrotect\u2122 estrus detection aids were applied on Day 14 at the time of CIDR removal and PG administration. The females assigned to the 7 &amp; 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 &amp; 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 \u00b1 2 h (nulliparous) or 66 \u00b1 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\u2013100 days after FTAI. The proportion of multiparous females with CL on Day 14 tended to be greater following treatment with 7 &amp; 7 Synch or 7 &amp; 7 + G (90% and 87%, respectively), as compared to females treated with 7 &amp; 7 + G + P (82%; p = 0.09). A greater proportion of multiparous females expressed behavioral estrus prior to FTAI when treated with 7 &amp; 7 + G + P (90%) as compared to multiparous females treated with 7 &amp; 7 + G (79%; p &lt; 0.002) or 7 &amp; 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 &amp; 7 Synch protocol effectively generated a convergent ovarian response among females with variable pretreatment luteal status but failed to enhance pregnancy rates to FTAI.<\/jats:p>","DOI":"10.3390\/ani15091329","type":"journal-article","created":{"date-parts":[[2025,5,5]],"date-time":"2025-05-05T03:05:15Z","timestamp":1746414315000},"page":"1329","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Tandem Administration of Prostaglandin F2\u03b1 and Gonadotropin-Releasing Hormone in Beef Heifers and Cows as a Convergent Presynchronization Method in the 7 &amp; 7 Synch Protocol"],"prefix":"10.3390","volume":"15","author":[{"given":"Lucas J.","family":"Palcheff","sequence":"first","affiliation":[{"name":"Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Genevieve M.","family":"VanWye","sequence":"additional","affiliation":[{"name":"Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kimberly R.","family":"Ricardo","sequence":"additional","affiliation":[{"name":"Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kendal L.","family":"Green","sequence":"additional","affiliation":[{"name":"Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Franklin J.","family":"Even","sequence":"additional","affiliation":[{"name":"Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Samantha R.","family":"Roberts","sequence":"additional","affiliation":[{"name":"Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adella B.","family":"Lonas","sequence":"additional","affiliation":[{"name":"Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3869-9748","authenticated-orcid":false,"given":"Christine M.","family":"Spinka","sequence":"additional","affiliation":[{"name":"School of Medicine, University of Missouri, Columbia, MO 65211, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1178-0316","authenticated-orcid":false,"given":"Scott E.","family":"Poock","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5272-9405","authenticated-orcid":false,"given":"Saulo","family":"Menegatti Zoca","sequence":"additional","affiliation":[{"name":"Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1851-5163","authenticated-orcid":false,"given":"Jessica N.","family":"Drum","sequence":"additional","affiliation":[{"name":"Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8804-4694","authenticated-orcid":false,"given":"Jordan M.","family":"Thomas","sequence":"additional","affiliation":[{"name":"Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.15232\/S1080-7446(15)31653-3","article-title":"Ovarian and Estrous Response of Suckled Beef Cows to the Select Synch Estrous Synchronization Protocol","volume":"16","author":"Geary","year":"2000","journal-title":"Prof. Anim. 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