Effective element of transfer of cloned embryos developed from somatic cells in buffaloes

There are many factors that affect transfer efficiency of cloned embryos developed from somatic cells.Such factors as expression of estrus,embryo types,embryo stage and season were investigated in this paper.The results showed that the estrus method had no significant effect on pregnancy rates following cloned embryo transfer.As far as embryo type,there was no difference on conception rate between fresh embryo and frozen embryo.The conception rate was 9.79% and 14.5%,respectively.The highest rate of pregnancy was observed in either fresh or frozen-thawed embryos at the 6 day stage.Different stages(5,6,7 and 8-10 d)of cloned embryos had no significant difference(fresh embryos P=0.260 7,frozen-thawed embryos P=0.065 2)in terms of pregnancy rates after transfer.The pregnancy rate after cloned embryo transfer was the best in autumn,which reached 16.06%,and had a significant difference compared to those in other seasons(P0.05).The following was in spring,but it had no difference between in summer and winter(P0.05).The above results indicated that the method of the somatic cell cloned embryos in embryo transfer is feasible and relatively low efficiency.