Superovulation Of Lambs And Its Fertilization In Vitro

According to the characteristic of prepubertal lambs(1-2 month) ovaries, which are sensitive to hormone and have less atresia,the technique of juvenile lambs superovulation is effective in obtaining oocytes from sheep ovary.The techniqueuvenile of lamb reproduction over early is an integrative embryonic biotechnique system including superovulation, ovum pick-up, fertilization in vitro, embryo transfer etc.The study was to optimize the technologies of superovulation,in vitro maturation (IVM),and in vitro fertilization(IVF)in lamb sheep,and effect of repeated hormone superovulation on the number of collected oocytes,and to compare the capability of ooeytes maturation, fertilization in vitro and early embryo development from juvenile lamb superovulation and adult ovary at slaughtethouse,and to study the effect of different pH of IVF medium on the development ability of embryos produced from juvenile sheep ooeytes. The objective of the present study was to improving the in vitro developmental capacity of juvenile lambs embryo obtained by superovulation and ovum pick-up (OPU). The results as follows:1. Lambs aged 6-weeks-old of Mountain Xi Mao Yang were superovulated by 2 treatments with FSH + LH and FSH+PMSG, lambs injected physiological saline group, number of follicles developed were 583 and number of oocytes recovered were 255. The oocytes were fertilized in vitro with the sperm capacitated by swim up after being cultured for 24 hours in vitro. The cleavage rates after 48h respectively were 11.4%, 22.7%. The treatment with FSH + LH had an advantage over method of FSH+PMSG (P<0.01).2 .One month later,superovulation was repeated on 8 lambs.The data shows that average oocytes obtained and average oocytes available for fertilization after the first treatment(54.0 vs 36.0) was more than the second time significantly (20.0 vs 15.0).3. The rate of in vitro maturation of juvenile lambs ooeytes was lower than that of adult sheep ooeytes from slaughtethouse(41.9%vs75.0%)(P<0.05).The eleavage rate and morula rate after fertilization invitro of juvenile lambs oocytes were lower than those of the adult sheep ooeyte significantly (44.4 % vs 37.5 %;75.8 % vs 70.0%) (P<0.01).4. The results of research on juvenile lambs IVF efficiency and developing capacity show that, Cleavage rate in 24h (60.4%)group was very significantly(P<0.01)higher than other two groups(25.0% vs 33.33%).5.different pH of IVF medium influence the cleavage rate .The results of research show that, When IVF medium pH was at the level of 7.3~7.5cleavage rate was much higher than pH = 7.6 ~ 7.8group.(56.6%vs 32.5%,P<0.05).