Dorper Sheep Crossbreeding Techniques

The reproductive techniques of mutton sheep, including estrus synchronization, semen cryopreservation, artificial insemination of fresh and cryopreserved semen, superovulation and embryo transfer etc, were systematically studied in this thesis, and some economic characters of the offspring that Dorper sheep (father) were hybridized with Hu sheep (mother) and Han sheep (mother) were identified and evaluated as well. A high efficiency, economical and practical reproductive technological system has been established in the study in order to lay a foundation for the breeding of high quality species of mutton sheep.The major result of the thesis are as follow:1. Three hundred of Hu sheep were induced estrus synchronization by five different methods and hybridized by artificial insemination of fresh semen from Dorper sheep. Rate of estrus synchronization and conception rate of artificial insemination were compared through statistical analysis.2. Four different diluents were used for the semen cryopreservation of Dorper sheep in straw. As a contrast, A group was used in the manufacture. After thawing, the highest motility was in B group. There were significant differences between B and other groups. The diluent of B group was used for artificial insemination. The non-estrus conception rate achieved 62% in two estrus cycle.3. Hu sheep were dealed with the national and imported external hormones. The superovulation,artificial insemination of fresh semen from Dorper sheep, the obtaining of embryo with micro-wounded operation and the embryo transfer techniques were firstly attempted. Both the result were ideal. It was statistically indicated that average ten oocytes were obtained from each ewe and conception rate achieved 100%.4. Hu sheep and Small Tail Han sheep were attempted to crossbreed economically by Dorper Sheep imported from New Zealand, respectively, in which Dorper sheep was used as a male parent and Hu sheep or Small Tail Han sheep as a female parent. Flocks of female Hu sheep and Small Tail Han Sheep were induced estrus synchronization by the external hormones and hybridized by artificial insemination of fresh semen from Dorper sheep. Conception rate, birth rate , changes of body weight and body size of the natal kidlets were recorded and compared with each other statistically. The results showed that there were significant differences of growing rate per day and changes of body size during six months periods between the lams hybrided Hu sheep with Dorper Sheep and the clean-bred lambs from Hu sheep as well as between She lambs hybrided Small Tail Han sheep with Dorper Sheep and the clean-bred lambs from Small Tail Han sheep. There were also significant differences of body weight per day between the hybrided Hu sheep and the hybrided Small Tail Han sheep within six months, but no statistical differences of body size between two kinds of hybrided lambs, respectively.The hybridization between Dorper sheep and Hu sheep or Dorper sheep and Small Tail Han sheep were both ideal modes of male and female parents. Both of Hu sheep and Small Tail Han sheep should be used as a female parent and further investigated in the breeding of high quality species of mutton sheep.