This study evaluated whether supplementation of embryo holding and incubation media with 10% camel calf serum (CCS) could improve the utilization of dromedary camel embryos under field conditions through two complementary experiments. In Experiment 1, hatched blastocysts recovered from superovulated donors were morphologically classified and transferred directly to recipients to determine the effect of embryo quality on pregnancy outcome. A total of 832 embryos were recovered, including 697 (83.8%) good-quality and 135 (16.2%) poor-quality embryos. Transfer of good-quality embryos resulted in significantly higher pregnancy rates at 10 days, 1 month, and 2 months after embryo transfer (ET) compared with poor-quality embryos (63.6%, 51.5%, and 47.1% vs. 31.9%, 23.0%, and 19.3%, respectively; p < 0.05). Early pregnancy loss (EPL) did not differ clearly between groups at 1 month but was higher (p < 0.05) in recipients of poor-quality embryos by 2 months (39.5% vs. 26.0%). In Experiment 2, 351 hatched blastocysts were recovered, of which 238 (67.8%) were good quality and 113 (32.2%) were poor quality. Good-quality embryos were either transferred directly or stored at 5°C for 24 or 48 h in holding medium (HM) with or without CCS. Direct transfer produced pregnancy rates of 62.9%, 55.1%, and 46.1% at 10 days, 1 month, and 2 months, respectively. Embryos cooled for 24 h in HM + CCS showed comparable rates (54.8%, 46.5%, and 40.5%), whereas embryos cooled in HM alone had lower rates (37.8%, 31.1%, and 26.7%). After 48 h of storage, pregnancy rates declined markedly in HM alone (27.3%, 21.2%, and 18.2%), but remained higher in HM + CCS (48.3%, 41.4%, and 34.5%). Poor-quality embryos were incubated for 24 h in HM + CCS before direct transfer or cooling. Following incubation, 39/54 (72.2%) folded embryos became nonfolded, and 48/113 (42.5%) changed size category. Embryos that increased in size from small to medium showed the highest pregnancy rates (72.2%, 61.1%, and 55.6%). Direct transfer of incubated poor-quality embryos resulted in pregnancy rates of 58.3%, 50.0%, and 41.6%, whereas embryos stored for 24 h in HM alone showed lower rates (31.3%, 25.0%, and 18.8%). Supplementation with CCS improved pregnancy outcomes during cooling (52.4%, 42.9%, and 33.3% after 24 h; 45.0%, 40.0%, and 30.0% after 48 h) compared with HM alone. These findings indicate that CCS can practically enhance embryo tolerance to short-term cooling and improves the developmental competence of compromised embryos, thereby increasing the pool of transferable embryos and improving the flexibility of camel ET programs.
Mansour et al. (Thu,) studied this question.
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