Abstract: The aim of the present study was to investigate the differences in embryo transfer effect and lamb early growth performance between small-tailed Han sheep and Mongolian sheep when they were used as the recipients. South African meat Merino sheep （n=11） and Australian white sheep （n=110） were used as donors, and small-tailed Han sheep （n=196） and Mongolian sheep （n=504） were used as recipients. The donors were subjected to superovulation and artificial insemination treatment, the total number of collected embryos and the number of available embryos was recorded, and the average number of available embryos per donor ewe and the qualified rate of embryos was calculated. The small-tailed Han sheep and Mongolian sheep were received simultaneous estrus and embryo transfer treatment, the number of lambs provided by the recipient ewes was recorded, and the reproduction rate was calculated. For the different varieties of recipient ewes, the average birth weight and survival rate of their lambs, the number and weight of their 70-day-old weaned lambs, the average daily gain of their lambs, and the average number of weaned lambs provided by each ewe were determined and compared, respectively. The results showed that a total of 549 available embryos were obtained from the donor ewes with an average of 4.54 embryos per sheep, and the embryo qualified rate was 82.56%. A total of 529 recipient ewes were qualified to receive embryo transfer treatment, and 240 lambs were obtained with an average reproduction rate of 45.37%. The small-tailed Han sheep had obviously higher estrus rate and reproduction rate compared to the Mongolian sheep. A total of 211 70-day-old weaned lambs were obtained, and the survival rate and average daily gain of the lambs was 87.92% and 280.00 g, respectively. There was no significant difference in birth weight of the lambs produced by small-tailed Han sheep and Mongolian sheep （P>0.05）. The weight of the 70-day-old weaned lambs and average daily gain of the lambs provided by small-tailed Han sheep were extremely significantly （P<0.01） and significantly （P<0.05） higher than that of Mongolian sheep, respectively. The survival rate of the lambs provided by Mongolian sheep was significantly higher than that of small-tailed Han sheep （P<0.05）. The average number of the weaned lambs （0.42） provided by per small-tailed Han sheep was slightly higher than that of Mongolian sheep （0.39）. Accordingly, small-tailed Han sheep had a slight advantage as embryo transfer recipient. The combined data suggest that both small-tailed Han sheep and Mongolian sheep can be used as recipients for embryo transfer in Hinggan League of Inner Mongolia.

Key words: small-tailed Han sheep, Mongolian sheep, simultaneous estrus, embryo transfer