The reproductive and lamb mortality data (n = 187) of the Local and crosses of Dorper × Local ewes following natural controlled breeding in Ethiopia were analysed. Data were collected during 2009-2011 at Sirinka ...The reproductive and lamb mortality data (n = 187) of the Local and crosses of Dorper × Local ewes following natural controlled breeding in Ethiopia were analysed. Data were collected during 2009-2011 at Sirinka breeding, evaluation and distribution site, eastern Amhara region of Ethiopia. Breed, lamb sex, birth season, birth year, birth type and ewes’ parity were considered as fixed effects. Data analyses were performed using general linear model procedures. Breed was a significant source of variation: the local sheep attained faster the age at first lambing than the crossbred ewe lambs (469 ± 8.45 vs. 555 ± 6.25 days, p < 0.0001), whereas the crossbred ewes weighed more than the local sheep ewes at the age of first lambing (32.7 ± 0.63 vs. 22.8 ± 0.43 kg, p < 0.0001). Birth year had also important influence on the age and weight at first lambing of ewes. Ewes showed better performance during the later study years, differences attributed due to the improved management advantages in later years. The crossbred and local ewes were comparable in their litter size, despite the fact that the lambing interval of crossbred ewes was longer than the local ewes (306 ± 4.62 vs. 287 ± 2.38 days). Additionally, there was no significant difference in mortality rate between the two breeds. This study confirms that the local ewes had higher annual reproductive rate than that of the crossbred sheep ewes (1.49 ± 0.02 vs. 1.37 ± 0.01 lambs) under the same environmental conditions. The present results suggested that better management and breeding program probably will increase the productivity of the local sheep.展开更多
This study was conducted to investigate the effects of different concentrations ofβ-mercaptoethanol on the development ability of oocytes in Dorper sheep at the age of 6 weeks.In this study,6 Dorper sheep of 6 weeks ...This study was conducted to investigate the effects of different concentrations ofβ-mercaptoethanol on the development ability of oocytes in Dorper sheep at the age of 6 weeks.In this study,6 Dorper sheep of 6 weeks old were chosen to induce oocyte collection in vivo by gonadotropin,and A and B grade cumulus oocyte complexes were obtained(COCs)with different concentrations of(0,50,70 and 100μmol/L)ofβ-mercaptoethanol in the mature liquid.The cleavage rate and blastocyst rate were counted after matured oocytes and capacitated sperm were co-incubated and fertilized eggs were cultivated.The results showed that compared with the cleavage rate(59.13%)and the blastocyst rate(12.17%)of the control group,the cleavage rates(60.87%,63.48%and 65.22%)and blastocyst rates(14.78%,17.39%and 21.74%)of the test groups I,II and III were higher(P>0.05),and the order was test group III>test group II>test group I>control group.The cleavage rate and blastocyst rate of the 100μmol/Lβ-mercaptoethanol group increased by 6.09 percentage points and 9.57 percentage points,respectively.It indicated that the addition of a certain amount ofβ-mercaptoethanol in the mature liquid could improve the developmental ability of oocytes and the quality of fertilized eggs of the 6-week-old Doper sheep.When theβ-mercaptoethanol concentration was within 100μmol/L,the cleavage rate and the blastocyst rate of oocytes were on the rise.The optimal concentration ofβ-mercaptoethanol in the mature liquid still needs further study.展开更多
This study was conducted to investigate the in-vitro production technology of embryos from young Dorper sheep, so as to provide technical support for the utilization of ovarian follicles in young Dorper sheep. Tests w...This study was conducted to investigate the in-vitro production technology of embryos from young Dorper sheep, so as to provide technical support for the utilization of ovarian follicles in young Dorper sheep. Tests were conducted from the induction of Dorper sheep of 4 to 8 weeks old using follicle stimulating hormone(FSH) and pregnant horse serum(PMSG), collection of oocytes, in-vitro oocyte maturation-fertilization-zygote cultivation and 2-4-cell-stage fertilized ovum transfer. The results showed that 585 oocytes were collected from eight Dorper sheep at the age of 4 and 8 weeks, with an average of 73.13 oocytes/sheep. 346 of the 2-4-cell-stage fertilized eggs were obtained, whose cleavage rate was 59.15%. 77 in-vitro fertilized eggs at 2-4-cell stage were transplanted into 17 recipient sheep, seven of which were pregnant and gave birth to 13 "test-tube sheep" with a conception rate of 41.18%. It is indicated that the hormone induction technique, in-vitro oocyte maturation-fertilization-zygote cultivation technique and 2-4-cell-stage fertilized ovum transfer technique used in this study can serve as effective techniques for the in-vitro production of embryos from Dorper sheep of 4-8 weeks old.展开更多
Since the birth of the first cloned sheep,somatic cell nuclear transfer technology has been successfully used to clone a variety of mammals.Cloned livestock have no apparent health risks,and the quality and safety of ...Since the birth of the first cloned sheep,somatic cell nuclear transfer technology has been successfully used to clone a variety of mammals.Cloned livestock have no apparent health risks,and the quality and safety of the cloned animal products are similar to non-cloned animals.The social behavior and environmental adaptability of postnatal cloned animals,especially when used for grassland farm production purposes,is unknown.In the present study,the cloned Dorper sheep equipped with GPS location devices were free-grazed in a harsh natural environment similar to conditions commonly experienced by Mongolian sheep.The main findings of this research were as follows.(1)Under free-grazing conditions,the cloned sheep showed excellent climatic and ecological adaptability.In extreme temperature conditions ranging from–30 to 40°C,the cloned sheep maintained acceptable body condition and behaved as other sheep.(2)The cloned sheep quickly adapted from a herd feeding strategy to the harsh environment and quickly exhibited a grazing regimen as other free-grazing sheep.(3)The cloned sheep exhibited free-grazing patterns and social behavior as other sheep.(4)The cloned sheep in the harsh environment thrived and produced healthy lambs.Overall,the cloned Dorper sheep exhibited excellent ecological adaptation,which is an important consideration for breeding meat sheep by cloning.The Dorper sheep readily adapted to the free-grazing conditions on the Mongolian plateau grassland,which attests to their ability to withstand harsh environmental conditions.展开更多
文摘The reproductive and lamb mortality data (n = 187) of the Local and crosses of Dorper × Local ewes following natural controlled breeding in Ethiopia were analysed. Data were collected during 2009-2011 at Sirinka breeding, evaluation and distribution site, eastern Amhara region of Ethiopia. Breed, lamb sex, birth season, birth year, birth type and ewes’ parity were considered as fixed effects. Data analyses were performed using general linear model procedures. Breed was a significant source of variation: the local sheep attained faster the age at first lambing than the crossbred ewe lambs (469 ± 8.45 vs. 555 ± 6.25 days, p < 0.0001), whereas the crossbred ewes weighed more than the local sheep ewes at the age of first lambing (32.7 ± 0.63 vs. 22.8 ± 0.43 kg, p < 0.0001). Birth year had also important influence on the age and weight at first lambing of ewes. Ewes showed better performance during the later study years, differences attributed due to the improved management advantages in later years. The crossbred and local ewes were comparable in their litter size, despite the fact that the lambing interval of crossbred ewes was longer than the local ewes (306 ± 4.62 vs. 287 ± 2.38 days). Additionally, there was no significant difference in mortality rate between the two breeds. This study confirms that the local ewes had higher annual reproductive rate than that of the crossbred sheep ewes (1.49 ± 0.02 vs. 1.37 ± 0.01 lambs) under the same environmental conditions. The present results suggested that better management and breeding program probably will increase the productivity of the local sheep.
基金Supported by Earmarked Fund for Construction of National Wool Sheep Industry Technology Research System(CARS-39-24)Fund for Science and Technology Innovation Team in Shanxi Province(201705D131028-20)
文摘This study was conducted to investigate the effects of different concentrations ofβ-mercaptoethanol on the development ability of oocytes in Dorper sheep at the age of 6 weeks.In this study,6 Dorper sheep of 6 weeks old were chosen to induce oocyte collection in vivo by gonadotropin,and A and B grade cumulus oocyte complexes were obtained(COCs)with different concentrations of(0,50,70 and 100μmol/L)ofβ-mercaptoethanol in the mature liquid.The cleavage rate and blastocyst rate were counted after matured oocytes and capacitated sperm were co-incubated and fertilized eggs were cultivated.The results showed that compared with the cleavage rate(59.13%)and the blastocyst rate(12.17%)of the control group,the cleavage rates(60.87%,63.48%and 65.22%)and blastocyst rates(14.78%,17.39%and 21.74%)of the test groups I,II and III were higher(P>0.05),and the order was test group III>test group II>test group I>control group.The cleavage rate and blastocyst rate of the 100μmol/Lβ-mercaptoethanol group increased by 6.09 percentage points and 9.57 percentage points,respectively.It indicated that the addition of a certain amount ofβ-mercaptoethanol in the mature liquid could improve the developmental ability of oocytes and the quality of fertilized eggs of the 6-week-old Doper sheep.When theβ-mercaptoethanol concentration was within 100μmol/L,the cleavage rate and the blastocyst rate of oocytes were on the rise.The optimal concentration ofβ-mercaptoethanol in the mature liquid still needs further study.
基金Supported by Earmarked Fund for Construction of National Wool Sheep Industry Technology Research System(CARS-39-24)Program for Science and Technology Development of Shanxi Province(20120311024-1)+1 种基金Fund for Science and Technology Innovation Team in Shanxi Province(201705D131028-20)Shanxi Agricultural Industry Development Technology Leading Fund(2017CYYL-08)
文摘This study was conducted to investigate the in-vitro production technology of embryos from young Dorper sheep, so as to provide technical support for the utilization of ovarian follicles in young Dorper sheep. Tests were conducted from the induction of Dorper sheep of 4 to 8 weeks old using follicle stimulating hormone(FSH) and pregnant horse serum(PMSG), collection of oocytes, in-vitro oocyte maturation-fertilization-zygote cultivation and 2-4-cell-stage fertilized ovum transfer. The results showed that 585 oocytes were collected from eight Dorper sheep at the age of 4 and 8 weeks, with an average of 73.13 oocytes/sheep. 346 of the 2-4-cell-stage fertilized eggs were obtained, whose cleavage rate was 59.15%. 77 in-vitro fertilized eggs at 2-4-cell stage were transplanted into 17 recipient sheep, seven of which were pregnant and gave birth to 13 "test-tube sheep" with a conception rate of 41.18%. It is indicated that the hormone induction technique, in-vitro oocyte maturation-fertilization-zygote cultivation technique and 2-4-cell-stage fertilized ovum transfer technique used in this study can serve as effective techniques for the in-vitro production of embryos from Dorper sheep of 4-8 weeks old.
基金This study was supported by the Basic Research Program of China(2012CB22306)the Integration and Application of Grassland Ecological Animal Husbandry Program of Inner Mongolia.
文摘Since the birth of the first cloned sheep,somatic cell nuclear transfer technology has been successfully used to clone a variety of mammals.Cloned livestock have no apparent health risks,and the quality and safety of the cloned animal products are similar to non-cloned animals.The social behavior and environmental adaptability of postnatal cloned animals,especially when used for grassland farm production purposes,is unknown.In the present study,the cloned Dorper sheep equipped with GPS location devices were free-grazed in a harsh natural environment similar to conditions commonly experienced by Mongolian sheep.The main findings of this research were as follows.(1)Under free-grazing conditions,the cloned sheep showed excellent climatic and ecological adaptability.In extreme temperature conditions ranging from–30 to 40°C,the cloned sheep maintained acceptable body condition and behaved as other sheep.(2)The cloned sheep quickly adapted from a herd feeding strategy to the harsh environment and quickly exhibited a grazing regimen as other free-grazing sheep.(3)The cloned sheep exhibited free-grazing patterns and social behavior as other sheep.(4)The cloned sheep in the harsh environment thrived and produced healthy lambs.Overall,the cloned Dorper sheep exhibited excellent ecological adaptation,which is an important consideration for breeding meat sheep by cloning.The Dorper sheep readily adapted to the free-grazing conditions on the Mongolian plateau grassland,which attests to their ability to withstand harsh environmental conditions.
