Effect of hormone pre-treatment of prepubertal sheep on the production and developmental capacity of oocytes in vitro and in vivo.

摘要

20 Merino lambs, 3-6 weeks of age, were assigned to 3 treatments which were timed to end simultaneously so that all animals could be slaughtered on the same day. The 1st group received an intramuscular injection of 50 鎔 oestradiol benzoate and (48h later) a 1.5 mg norgestomet implant left in situ for 9 days. The treatment regime was repeated twice thereafter. On day 7 after the last implant insertion, each lamb received 400 IU PMSG and 6 mg FSH. Group 2 animals received the oestradiol and norgestomet treatment only once followed by PMSG and FSH. The 3rd group received PMSG and FSH only. The reproductive tracts were removed for oocyte collection 24 h after FSH. Reproductive tracts were also collected from 31 prepubertal (16-24 weeks of age) sheep(controls). The number of antral follicles recovered per ovary was similar for the 3 treatment group and higher than in controls (30.9-41.8 vs. 6.3; P<0.05). In vitro maturation and monospermic fertilization rates were similar for all groups. The percentage of blastocysts per cleaved oocyte was higher (P<0.05) for group 2 (50.5) than for group 1 (32.9), group 3 (24.3) or controls (11.8). After transfer of embryos, viable fetuses were obtained at slaughter on day 93 of pregnancy from all groups.