Abstract: 【Objective】 The critical problem of meat sheep industry in China is that there are no self-owned high yield and superior breed, which lead to low per meat productivity, inferior quality and less profit. The per meat productivity can be improved through hybridization between local sheep and foreign breeds. However, some excellent traits of our native breeds disappeared on account of hybridization without planning and design, as a result of the complexity of crossbred and difficult matched technique. Moreover, in the long run, the key measure of enhancing local breed meat performance and filling in the blank of special meat breed is breeding a new breed according to the national situation of China and agricultural region features. Hanper mutton sheep is a flock of which was bred based on the maternal parent Small-taied Han sheep and Dorper sheep as paternal subject with fecundity gene BMPR1B (A746G) as molecular marker through several years of selection and cultivation in agricultural regions. The aim of this study is to examine the reproductive productivity of Hanper mutton sheep for farther selection and breeding. 【Method】The reproduction related traits, including litter size, litter size interval (the interval from current childbirth to next time), gestation period ( period from mating to delivery) and first birthing age (the period from birth to first parturition), the effect of parity on litter size, proportion distribution of birthing ewes in one year of Hanper and Small-tailed Han sheep ewes, and litter size month on next birthing interval of Hanper mutton sheep, were analyzed.【Result】The results indicated that there were no significant differences in first birthing age ((440.46±92.40) d vs (490.48±42.71) d), gestation period ((145.93±4.80) d vs (147.95±4.41) d), birthing interval ((300.42±72.85) d vs (275.94±48.42) d), litter size (1.86±0.71 vs 1.82±0.50) between Hanper and Small-tailed Han sheep (P＞0.05). The effect of parity on litter size was significant in Hanper sheep, and the litter size per parity was increased with the parity gradually, and the peak value of fifth parity was 2.15, and the litter size declined from the fifth parity. The first quarter was litter size peak of Hanper sheep ewes which were mated in autumn of last year, the proportion of birthing ewes in February was 15.82% which means that the most number of pregnancy ewes in September. The birthing ewes proportion between April and September was lower than the theory average value, and the percentage of June to August was the least. The proportion of birthing ewes of Small-tailed Han sheep between April and July was lower than the average data. The minimum (4.77%) was in June. The number of birthing ewes between August and March of next year was more than the average value which was 8.33%. The litter pattern showed some seasonal characters, but the difference was not obvious. There was a certain influence of birthing month on the next delivery interval. The long time was 323 days from February to next birthing lambs, and the short interval from littering to next time was about 8 months during July to October. 【Conclusion】Hanper mutton sheep have inherited the reproduction performances of their maternal parent Small-tailed Han sheep. There were no significant differences in first birthing age, gestation period, birthing interval, and litter size. The influences of parity on litter size, and the effect of birthing month effect on interval to next time were prominent.

Key words: Hanper Mutton sheep, litter size, birthing interval, first birthing age, parity, birthing month