{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,29]],"date-time":"2026-08-29T00:40:12Z","timestamp":1787964012530,"version":"build-2784847793"},"reference-count":43,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,1]],"date-time":"2026-01-01T00:00:00Z","timestamp":1767225600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["NRF-2021R1C1C2013954"],"award-info":[{"award-number":["NRF-2021R1C1C2013954"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The success rate of embryo transfer (ET) is influenced by various factors, including embryo quality, environmental conditions, and recipient cows. This study examines the impact of ET on embryo success rates using embryos produced using the ovum pickup method, with fresh and frozen embryos generated on day 7 after in vitro fertilization and subsequently implanted into recipient cows. The factors that contributed to the success rate of ET were investigated, with a focus on embryo type, parity, and farm management. Furthermore, metabolic profile tests were conducted to determine the factors underlying the observed differences in pregnancy rates across the farms. The analysis revealed that pregnancy rates did not significantly differ according to embryo type or parity. However, significant differences (p &lt; 0.05) were observed in the glucose, cholesterol, non-esterified fatty acid, total protein, globulin, albumin\/globulin, and aspartate aminotransferase levels of the recipients. Furthermore, a comparison of farms with high and low pregnancy rates revealed significant differences in the glucose, cholesterol, total protein, albumin, globulin, and albumin\/globulin levels (p &lt; 0.05). Differences between farms were associated with the feed management strategy, which highlights the significance of optimal recipient cow management.<\/jats:p>","DOI":"10.3390\/ani16010125","type":"journal-article","created":{"date-parts":[[2026,1,2]],"date-time":"2026-01-02T09:18:56Z","timestamp":1767345536000},"page":"125","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Optimization of the Embryo Transfer Technique in the Korean Native Cattle: Effects of Key Influencing Factors"],"prefix":"10.3390","volume":"16","author":[{"given":"Seungki","family":"Jung","sequence":"first","affiliation":[{"name":"Veterinary Medical Center, Laboratory of Veterinary Embryology and Biotechnology (VETEMBIO), College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea"},{"name":"ET Biotech Co., Ltd., Jangsu 55609, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2639-3231","authenticated-orcid":false,"given":"Heejae","family":"Yang","sequence":"additional","affiliation":[{"name":"Cocoon Inc., Cheongju 28161, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yeonsub","family":"Jung","sequence":"additional","affiliation":[{"name":"ET Biotech Co., Ltd., Jangsu 55609, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Minki","family":"Lee","sequence":"additional","affiliation":[{"name":"Cocoon Inc., Cheongju 28161, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyeonseok","family":"Sul","sequence":"additional","affiliation":[{"name":"ET Biotech Co., Ltd., Jangsu 55609, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yeon-Gil","family":"Jung","sequence":"additional","affiliation":[{"name":"ET Biotech Co., Ltd., Jangsu 55609, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7233-6409","authenticated-orcid":false,"given":"Joohyeong","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Companion Animal Industry, Semyung University, Jecheon 27136, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6011-2555","authenticated-orcid":false,"given":"Sang-Hwan","family":"Hyun","sequence":"additional","affiliation":[{"name":"Veterinary Medical Center, Laboratory of Veterinary Embryology and Biotechnology (VETEMBIO), College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea"},{"name":"Institute of Stem Cell & Regenerative Medicine (ISCRM), Chungbuk National University, Cheongju 28644, Republic of Korea"},{"name":"Vet-ICT Convergence Education and Research Center (VICERC), Chungbuk National University, Cheongju 28644, Republic of Korea"},{"name":"Chungbuk National University Hospital, Cheongju 28644, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"690","DOI":"10.1016\/j.theriogenology.2008.09.031","article-title":"Comparison of embryo yield and pregnancy rate between in vivo and in vitro methods in the same Nelore (Bos indicus) donor cows","volume":"71","author":"Pontes","year":"2009","journal-title":"Theriogenology"},{"key":"ref_2","first-page":"22","article-title":"2021 statistics of embryo production and transfer in domestic farm animals","volume":"40","author":"Viana","year":"2022","journal-title":"Embryo Technol. Newsl."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"100752","DOI":"10.1016\/j.animal.2023.100752","article-title":"Review: Current status of corpus luteum assessment by Doppler ultrasonography to diagnose non-pregnancy and select embryo recipients in cattle","volume":"17","author":"Pugliesi","year":"2023","journal-title":"Animal"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1016\/j.theriogenology.2025.01.009","article-title":"Strategic use of estrus intensity to combine timed artificial insemination and embryo transfer in large-scale cattle reproduction programs","volume":"235","author":"Morotti","year":"2025","journal-title":"Theriogenology"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1555","DOI":"10.1111\/rda.14019","article-title":"Effect of flunixin meglumine treatment during and after embryo transfer on the pregnancy rate in cattle","volume":"56","author":"Karasahin","year":"2021","journal-title":"Reprod. Domest. Anim."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1111\/rda.13623","article-title":"Evaluation of the factors that affect the pregnancy rates during embryo transfer in beef heifers","volume":"55","author":"Alkan","year":"2020","journal-title":"Reprod. Domest. Anim."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1095\/biolreprod62.4.847","article-title":"Energy metabolism in preimplantation bovine embryos derived in vitro or in vivo","volume":"62","author":"Khurana","year":"2000","journal-title":"Biol. Reprod."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"972","DOI":"10.1002\/mrd.20677","article-title":"Temporal expression of transcripts related to embryo quality in bovine embryos cultured from the two-cell to blastocyst stage in vitro or in vivo","volume":"74","author":"Corcoran","year":"2007","journal-title":"Mol. Reprod. Dev."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1262\/jrd.2019-100","article-title":"Comparison of gene expression and mitochondria number between bovine blastocysts obtained in vitro and in vivo","volume":"66","author":"Noguchi","year":"2020","journal-title":"J. Reprod. Dev."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"949","DOI":"10.1016\/j.theriogenology.2009.06.013","article-title":"Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer","volume":"72","author":"Siqueira","year":"2009","journal-title":"Theriogenology"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.anireprosci.2003.10.009","article-title":"Relationship between level of milk production and estrous behavior of lactating dairy cows","volume":"81","author":"Lopez","year":"2004","journal-title":"Anim. Reprod. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1016\/j.theriogenology.2020.09.033","article-title":"Comparison of the 7 & 7 Synch protocol and the 7-day CO-Synch + CIDR protocol among recipient beef cows in an embryo transfer program","volume":"158","author":"Bonacker","year":"2020","journal-title":"Theriogenology"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1834","DOI":"10.1016\/j.theriogenology.2016.05.032","article-title":"Factors affecting the success of a large embryo transfer program in Holstein cattle in a commercial herd in the southeast region of the United States","volume":"86","author":"Ferraz","year":"2016","journal-title":"Theriogenology"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1262\/jrd.2022-112","article-title":"Effects of the temperature-humidity index on conception rates in Holstein heifers and cows receiving in vitro-produced Japanese Black cattle embryos","volume":"69","author":"Nishisozu","year":"2023","journal-title":"J. Reprod. Dev."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"36","DOI":"10.2527\/1997.77suppl_236x","article-title":"Strategies for managing reproduction in the heat-stressed dairy cow","volume":"77","author":"Hansen","year":"1999","journal-title":"J. Anim. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.theriogenology.2019.12.001","article-title":"Cryopreservation induces higher oxidative stress levels in Bos indicus embryos compared with Bos taurus","volume":"143","author":"Alarcon","year":"2020","journal-title":"Theriogenology"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"684","DOI":"10.1111\/rda.12354","article-title":"Forced collapse of the blastocoel cavity improves developmental potential in cryopreserved bovine blastocysts by slow-rate freezing and vitrification","volume":"49","author":"Min","year":"2014","journal-title":"Reprod. Domest. Anim."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Jung, S., Sul, H., Oh, D., Jung, Y.G., Lee, J., and Hyun, S.H. (2024). Slow freezing cryopreservation of Korean bovine blastocysts with an additional sucrose pre-equilibration step. Front. Vet. Sci., 11.","DOI":"10.3389\/fvets.2024.1400899"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"117399","DOI":"10.1016\/j.theriogenology.2025.117399","article-title":"L-proline supplementation in the freezing medium enhances the viability and quality of bovine blastocysts after slow freezing and thawing","volume":"240","author":"Jung","year":"2025","journal-title":"Theriogenology"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"100166","DOI":"10.1016\/j.animal.2020.100166","article-title":"Effects of nutrient restriction on the metabolic profile of Bos indicus-influenced and B. taurus suckled beef cows","volume":"15","author":"Fontes","year":"2021","journal-title":"Animal"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1003","DOI":"10.1292\/jvms.64.1003","article-title":"Use of every ten-day criteria for metabolic profile test after calving and dry off in dairy herds","volume":"64","author":"Kida","year":"2002","journal-title":"J. Vet. Med. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1269","DOI":"10.1292\/jvms.67.1269","article-title":"Results of metabolic profile test in Japanese black cattle with growth retardation","volume":"67","author":"Takasu","year":"2005","journal-title":"J. Vet. Med. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"181","DOI":"10.3168\/jds.2012-5619","article-title":"Concentrations of nonesterified fatty acids and glucose in blood of periparturient dairy cows are indicative of pregnancy success at first insemination","volume":"96","author":"Garverick","year":"2013","journal-title":"J. Dairy Sci."},{"key":"ref_24","first-page":"344","article-title":"Evaluation and classification of bovine embryos","volume":"10","author":"Bo","year":"2013","journal-title":"Anim. Reprod."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2541","DOI":"10.1007\/s11250-020-02287-6","article-title":"Effect of embryo quality and developmental stages on pregnancy rate during fresh embryo transfer in beef heifers","volume":"52","author":"Erdem","year":"2020","journal-title":"Trop. Anim. Health Prod."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1262\/jrd.2019-025","article-title":"Direct transfer of frozen-thawed bovine embryos and its application in cattle reproduction management","volume":"65","author":"Dochi","year":"2019","journal-title":"J. Reprod. Dev."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1074","DOI":"10.1111\/rda.14182","article-title":"Effect of addition of ascorbate, dithiothreitol or a caspase-3 inhibitor to cryopreservation medium on post-thaw survival of bovine embryos produced in vitro","volume":"57","author":"Zolini","year":"2022","journal-title":"Reprod. Domest. Anim."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1262\/jrd.2023-071","article-title":"Carnosine supplementation in cryopreservation solution improved frozen-thawed bovine embryo viability","volume":"70","author":"Ishii","year":"2024","journal-title":"J. Reprod. Dev."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.1016\/S0093-691X(98)00053-3","article-title":"Direct transfer of bovine embryos frozen-thawed in the presence of propylene glycol or ethylene glycol under on-farm conditions in an integrated embryo transfer program","volume":"49","author":"Dochi","year":"1998","journal-title":"Theriogenology"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/j.theriogenology.2024.07.001","article-title":"A retrospective analysis of conception per embryo transfer in dairy cattle in South Korea","volume":"226","author":"Lee","year":"2024","journal-title":"Theriogenology"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/S0378-4320(05)80001-6","article-title":"Ovarian endocrine activity and development of ovarian follicles during the postpartum interval in beef cows","volume":"24","author":"Dimmick","year":"1991","journal-title":"Anim. Reprod. Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"727","DOI":"10.1530\/rep.1.00080","article-title":"Effects of parity and body condition at parturition on endocrine and reproductive parameters of the cow","volume":"127","author":"Meikle","year":"2004","journal-title":"Reproduction"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1292\/jvms.64.557","article-title":"The metabolic profile test: Its practicability in assessing feeding management and periparturient diseases in high yielding commercial dairy herds","volume":"64","author":"Kida","year":"2002","journal-title":"J. Vet. Med. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1153","DOI":"10.1016\/j.theriogenology.2010.11.027","article-title":"Comparison of progesterone-based protocols with gonadotropin-releasing hormone or estradiol benzoate for timed artificial insemination or embryo transfer in lactating dairy cows","volume":"75","author":"Vasconcelos","year":"2011","journal-title":"Theriogenology"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1016\/j.theriogenology.2017.10.043","article-title":"Flunixin meglumine improves pregnancy rate in embryo recipient beef cows with an excitable temperament","volume":"107","author":"Kasimanickam","year":"2018","journal-title":"Theriogenology"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"147","DOI":"10.5713\/ab.21.0079","article-title":"A comparative analysis of rumen pH, milk production characteristics, and blood metabolites of Holstein cattle fed different forage levels for the establishment of objective indicators of the animal welfare certification standard","volume":"35","author":"Baek","year":"2022","journal-title":"Anim. Biosci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1262\/jrd.2024-092","article-title":"Factors influencing in vivo embryo production in Japanese Black donors: The role of anti-Mullerian hormone and inflammation parameters","volume":"71","author":"Okawa","year":"2025","journal-title":"J. Reprod. Dev."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1403","DOI":"10.1292\/jvms.13-0543","article-title":"Improvement of preimplantation development of in vitro-fertilized bovine zygotes by glucose supplementation to a chemically defined medium","volume":"76","author":"Sakagami","year":"2014","journal-title":"J. Vet. Med. Sci."},{"key":"ref_39","first-page":"55","article-title":"A field study on glucose, non-esterified fatty acids, beta-hydroxybutyrate and thyroid hormones in dairy cows during the breeding period in Fars province, Iran","volume":"20","author":"Omidi","year":"2019","journal-title":"Iran. J. Vet. Res."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1485","DOI":"10.1292\/jvms.12-0235","article-title":"Improvement of superovulatory response and pregnancy rate after transfer of embryos recovered from Japanese Black cows fed rumen bypass polyunsaturated fatty acids","volume":"75","author":"Takahashi","year":"2013","journal-title":"J. Vet. Med. Sci."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"743","DOI":"10.1292\/jvms.23-0081","article-title":"Albumin and other metabolic parameters as potential indicators of purulent vaginal discharge in dairy cows during the transition period","volume":"85","author":"Thongrueang","year":"2023","journal-title":"J. Vet. Med. Sci."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"539","DOI":"10.21451\/1984-3143-AR2019-0057","article-title":"Inflammation: Friend or foe of bovine reproduction?","volume":"16","author":"Chastant","year":"2019","journal-title":"Anim. Reprod."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1017\/S0022029900019889","article-title":"Relationships between blood composition and fertility in dairy cows\u2014A field study","volume":"44","author":"Rowlands","year":"1977","journal-title":"J. Dairy Res."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/1\/125\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,6]],"date-time":"2026-01-06T05:12:56Z","timestamp":1767676376000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/1\/125"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,1]]},"references-count":43,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["ani16010125"],"URL":"https:\/\/doi.org\/10.3390\/ani16010125","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,1]]}}}