Faster-developing buffalo embryos produced in vitro demonstrate higher quality, enhanced pregnancy rates, and...

In vitro embryo production (IVEP) is widely adopted as a tool to genetically improve the livestock, including cattle and buffalo; however, the substantial scope remains which demands further optimization. It has been observed that embryos exhibit variable developmental kinetics during in vitro culture (IVC); therefore, it is crucial to identify their developmental potential and the underlying biological mechanisms. So, developmental competence and pregnancy outcomes of embryos that attained the blastocyst stage on days 5, 6, and 7 post-insemination were compared in present study. Furthermore, transcriptomic profiling of fast-developing (Day 5) and slow-developing (Day 7) embryos was evaluated. The present data revealed that percentage of embryos developed to blastocyst stage was significantly higher on day 5 as compared to day 6 and 7. Morphological analysis revealed higher percentage of code 1 embryos on day 5 compared to day 6 and day 7. Embryo staining analysis showed that day 5 blastocysts contained significantly more cells per blastocyst than day 6 or day 7 blastocysts. Furthermore, the pregnancy rate for day 5 (36.5 ± 5.9%) blastocysts was significantly higher than that for day 7 (9.8 ± 5.3%) blastocysts, whereas it showed non-significant trend with day 6 (20.1 ± 4.6%) blastocysts. Transcriptomic analysis identified differentially expressed genes between day 5 and day 7 blastocysts, particularly those associated with cell proliferation, transcriptional regulation, positive regulation of proliferation, and CTNNB1-mediated cell adhesion. The findings suggest that day 5 blastocysts, which develop more rapidly, exhibit increased expression of adhesion-related genes, potentially enhancing their implantation capacity. This study introduces an innovative approach for selecting embryos in buffalo embryo transfer practices and offers valuable insights for optimizing embryo culture protocols.