Effect On The Pregnancy Rate Of Bovine Embryo After Co-transfer With Embryo Tissues

Bovine embryo transfer includes embryo preservation, embryo sexeing, estrus synchronization of donor and recipient, superovulation and transfer. The bottleneck which is low pregnancy rate restrict development of embryo transfer. For solving the difficulty of embryo transfer, bovine embryos were co-transferred with the grade 3 embryo, embryo trophoblast or embryo mass to accelerate industrialization spread on embryo transfer.Sexed embryo was thawed at water temperature of 35℃, 30℃, 25℃, the blastocyst rate were 52.50%, 45.00%, 57.50%, respectively, which had no significant difference between three groups(p>0.05). Sexed embryo was cultured by embryo medium CR1 and Holding, the culture effect of solution CR1 was all better than that of Holding in both CO2 incubator(68.4% vs 58.8%) and isothermal test tube(42.9% vs38.0%), but there was no significant difference in two groups(p>0.05).In the same culture soution the developmental rate of blastocyst in CO2 incubator was better than that of isothermal test tube. Embryo blastocyst rate was 31.25%-47.22%, which cultured in the isothermal test tube-Holding system within 7-18h, and the best blastocyst rate 47.22% was obtained at 10h. The best blastocyst rate was 47.62% when sexed embryo was culture by CO2 incubator-Holding system within 2-7h.The result indicated that the pregnancy rate of grade 3 and 3 embryo group was 11.76%, remarkable lower than that of 1 and 3 embryo group(63.64%) and that of 2 and 3 embryo group(50.00%)(p<0.01); the pregnancy rate of grade 1 and 3 embryo group was higher than that of 1 embryo group by 11.64 percentage point (63.64% vs 52.00%), the pregnancy rate of grade 2 and 3 embryo group was higher than that of 2 embryo group by 8.62 percentage point (50.00% vs 41.38), there was no significant difference in both two groups(p>0.05). The pregnant rate of sexed frozen embryo co-transfer with grade 3 embryo group was higher than that of the control group by 19.30 percentage point (66.67% vs. 47.37%)(p>0.05); The pregnant rate of sexing embryo co-transfer with grade 3 embryo group was higher than that of the control group by 6.43 percentage point (52.38% vs. 45.95%)(p>0.05). There was no significant difference between the pregnant rate of sexed embryo and sexing embryo (47.37% vs. 45.95%)(p>0.05).Reguler embryo co-transfer with embryo trophoblast group had the best pregnant rate of 80.00%, higher than that of the control group(60.42%),but there was no significant difference(p>0.05).The pregnant rate sexed frozen embryo co-transfer with embryo trophoblast group was higher than that of the control group (51.15% vs 43.82%), which had no significant difference (p>0.05). The pregnant rate of sexed frozen embryo co-transfer with embryo mass group was 62.50%, which was higher than that of the control group (43.82%)(p>0.05). The pregnant rate sexed fresh embryo co-transfer with fresh trophoblast group was higher than that of the control group (55.56% vs 46.15%), which had no significant difference (p>0.05). Sexed fresh embryo co-transferred embryo co-transfer with embryo mass group had the best pregnant rate of 68.75%, which was higher than that of the control group (46.15%), but there was no significant difference (p>0.05).In summary, Bovine embryos were co-transferred with the grade of 3 embryo, embryo trophoblast or embryo mass can all improve the pregnancy rate of embryo transfer.