Effect of Lamb Age and in vitro Culture System of Oocytes on JIVET Technology

[Objectives] This study was conducted to investigate the effects of lamb age and in vitro culture system of oocytes on the results of juvenile in vitro embryo transfer( JIVET). [Methods]Ten Dorper × small-tailed Han lambs aged 5 to 10 weeks were induced to superovulate via i. p. injection of pregnant mare's serum gonadotropin( PMSG). The oocytes were matured in basal maturation solution or modified maturation solution,which was prepared by adding 200 μmol/L cysteine to the basal maturation solution. Then,the oocytes were fertilized in fertilization medium I containing 2% estrus sheep serum( ESS) or fertilization medium II containing 3 mg/ml bull serum albumin( BSA). Finally,the number of oocytes,oocyte maturation rate and cleavage rate of the lambs of different ages were determined. [Results]The average number of oocytes recovered per lamb was( 111. 00 ± 16. 97),( 139. 50 ± 28. 99),( 108. 50 ± 17. 68) and( 42. 00 ± 11. 31) for5-,7-,8-and 10-week-old Dorper × small-tailed Han lambs,respectively. The number of oocytes obtained from 5-,7-and 8-week-old lambs was significantly higher than that from 10-week-old lambs( P < 0. 05),but there was no significant difference among 5-,7-and 8-week-old lambs( P > 0. 05). The maturation rate of oocytes cultured in modified maturation solution was 3. 64% higher than that in basal maturation solution. The cleavage rate of oocytes in fertilization medium I was very significantly higher than that in fertilization medium II( P < 0. 01). [Conclusions] The results of JIVET can be improved by harvesting oocytes from lambs aged 5-8 weeks,adding a certain amount of cysteine into oocyte maturation solution,and a certain amount of ESS into fertilization medium.

Effects of β-mercaptoethanol Concentrations on Developmental Ability of Oocytes in 6-week-old Dorper Sheep

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.