
%0 Journal Article
%A O'Brien, J. K. 
%A Beck, N. F. G. 
%A Maxwell, W. M. C. 
%A Evans, G. 
%T Effect of hormone pre-treatment of prepubertal sheep on the production and developmental capacity of oocytes <emph type="2">in vitro</emph> and <emph type="2">in vivo</emph>
%J Reproduction, Fertility and Development
%D 1998/03/23
%V 9
%N 6
%P 625-632
%K 
%R https://doi.org/10.1071/R97047
%U https://www.publish.csiro.au/paper/R97047 
%X Twenty 36-week-old Merino lambs were given either 3, 1 or 0 treatments of 50 &#181;g oestradiol benzoate and (48 h later) a 1&#183;5 mg Norgestamet implant left in situ for 9 days (3-, 1- and 0CYCLE+G). On Day 7 after the last implant insertion, and on the same day for 0CYCLE+G, each lamb received 400 I.U. pregnant mare serum gonadotrophin and 6 mg follicle-stimulating hormone (FSH). The reproductive tracts were removed for oocyte collection 24 h after FSH. Reproductive tracts were also collected from 16-24-week-old lambs (n = 31) (0CYCLEG). The number of antral follicles per ovary was similar for the 3-, 1- and 0CYCLE+G treatments. Similar rates of in vitro maturation and monospermic fertilization were obtained for all groups. The proportion of blastocysts per cleaved oocyte was higher for 1CYCLE+G (50&#183;5%) than for 3CYCLE+G (32&#183;9%), 0CYCLE+G (24&#183;3%), and 0CYCLEG (11&#183;8%) (P &#60; 0&#183;05). Viable fetuses were obtained at Day 93 of pregnancy after transfer of embryos from all treatments. These results indicate that a single treatment with oestrogen and progesterone, prior to gonadotrophin stimulation, will increase the yield and developmental capacity of oocytes from prepubertal sheep. 
