Improved pregnancy rate and sex ratio in fresh/frozen in vivo derived embryo transfer of Hanwoo (Bos taurus coreanae) cows

This study aimed to assess the effects of embryonic developmental stage, quality grade, and fresh or frozen/thawed conditions on pregnancy rate sex ratio live offspring in Hanwoo (<italic>Bos taurus coreanae</italic>) cows. The stage <italic>in vivo</italic>-derived (IVD) transferred embryos were evaluated using standard criteria International Embryo Technology Society. recipient cows synchronized conventional (estradiol benzoate progesterone) protocols before embryo transfer. Embryos 297 cows, was monitored for 60–70 days after rates 56.90% 52.49%, respectively. Pregnancy varied according (56.18% grade 1 vs. 36.67% 2). also by cryopreservation (67.86% 63.49% 4-1, 64.00% 54.72% 5-1, 50.00% 47.83% 6-1, embryos, respectively). For 7-1, 72.73% 20.00% embryos. In 66 5:5, whereas it 4:6 among 95 miscarriage approximately 3% higher than Seasonal fertility 55% 57% spring, 63.08% 53.57% summer, 68.42% 66.67% autumn, respectively, with highest observed autumn (72.73% 27.27%). current data revealed no significant differences between IVD However, there a lower advanced-stage (stage 7-1). provides comprehensive results better optimization transfer cattle obtain desired rate, calves. These provide important insights into factors that influence viability success may have practical applications improving breeding programs reducing production costs.