The objective of this study was to evaluate the effect of embryo quality and developmental stages on pregnancy rate in beef heifer recipients. The present study used 168 Simmental breed cows as donors, and 618 beef cattle breed heifers as recipients. The quality and developmental stages of the collected embryos were evaluated according to the criteria specified by the International Embryo Technology Society. Accordingly, the embryos in the compact morula, early blastocyst, blastocyst, and expanded blastocyst stages that were of Code I (excellent) and Code II (good) quality levels were transferred as fresh embryos to the recipient heifers. Prior to the transfer, the recipients were synchronized using the Ovsynch protocol, and the embryos obtained were transferred to 618 beef heifers. Pregnancy examinations were performed on days 30 and 60. On day 30, the pregnancy rates with Code I and Code II embryos were determined as 44.15% and 32.58%, respectively. According to the developmental stages, the pregnancy rates with Code I quality compact morula, early blastocyst, blastocyst, and expanded blastocyst were determined as 44.64%, 45.67%, 45.83%, and 33.33%, respectively. The rates of pregnancy with Code II quality compact morula, early blastocyst, and blastocyst were determined as 32.03%, 32.14%, and 50.0%, respectively. In conclusion, the pregnancy rates with Code I quality embryos were found to be higher compared with Code II embryos (P < 0.05). It was also determined that the embryonic developmental stages had no effect on the pregnancy rate (P > 0.05).

中文翻译：

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牛小母牛新鲜胚胎移植过程中胚胎质量和发育阶段对妊娠率的影响。

这项研究的目的是评估牛小母牛受精者胚胎质量和发育阶段对妊娠率的影响。本研究使用168只西门塔尔牛作为供体，618只肉牛小母牛作为受主。根据国际胚胎技术协会指定的标准评估收集的胚胎的质量和发育阶段。因此，将具有I级（优异）和II级（良好）质量水平的紧密桑，早期胚泡，胚泡和扩大胚泡阶段的胚作为新鲜胚转移到受精母牛。在转移之前，使用Ovsynch协议将接收者同步，并将获得的胚胎转移到618头小母牛。在第30和60天进行了怀孕检查。在第30天，确定具有I代和II代胚胎的怀孕率分别为44.15％和32.58％。根据发育阶段，确定具有Code I质量紧密桑，早期胚泡，胚泡和扩张胚泡的妊娠率分别为44.64％，45.67％，45.83％和33.33％。确定具有Code II质量的紧密桑，早期胚泡和胚泡的妊娠率分别为32.03％，32.14％和50.0％。总之，发现具有Code I品质胚胎的妊娠率高于Code II胚胎（P <0.05）。还确定了胚胎发育阶段对妊娠率没有影响（P> 0.05）。根据发育阶段，确定具有Code I质量紧密桑，早期胚泡，胚泡和扩张胚泡的妊娠率分别为44.64％，45.67％，45.83％和33.33％。确定具有Code II质量的紧密桑，早期胚泡和胚泡的妊娠率分别为32.03％，32.14％和50.0％。总之，发现具有Code I品质胚胎的妊娠率高于Code II胚胎（P <0.05）。还确定了胚胎发育阶段对妊娠率没有影响（P> 0.05）。根据发育阶段，确定具有Code I质量紧密桑，早期胚泡，胚泡和扩张胚泡的妊娠率分别为44.64％，45.67％，45.83％和33.33％。确定具有Code II质量的紧密桑，早期胚泡和胚泡的妊娠率分别为32.03％，32.14％和50.0％。总之，发现具有Code I品质胚胎的妊娠率高于Code II胚胎（P <0.05）。还确定了胚胎发育阶段对妊娠率没有影响（P> 0.05）。确定具有Code II质量的紧密桑，早期胚泡和胚泡的妊娠率分别为32.03％，32.14％和50.0％。总之，发现具有Code I品质胚胎的妊娠率高于Code II胚胎（P <0.05）。还确定了胚胎发育阶段对妊娠率没有影响（P> 0.05）。确定具有Code II质量的紧密桑，早期胚泡和胚泡的妊娠率分别为32.03％，32.14％和50.0％。总之，发现具有Code I品质胚胎的妊娠率高于Code II胚胎（P <0.05）。还确定了胚胎发育阶段对妊娠率没有影响（P> 0.05）。