Journal Article


A.C.O. Evans
P. Lonergan
A Donovan
P. Duffy
C M O' Meara
F Ward
J P Hanrahan
S Fair



embryonic development insemination artificial blastocyst physiology cytology sheep time factors crosses genetic animals laparoscopy female embryology genetics pregnancy oocytes cells cultured veterinary breeding

The difference in embryo quality between Belclare and Suffolk ewes is not due to differences in oocyte quality. (2005)

Abstract We have previously reported that the percentage of fertilized oocytes which reached the blastocyst stage by Day 6 after AI with frozen-thawed semen was higher for Belclare (94%) than Suffolk (59%) ewes. This may reflect differences in the timing of fertilization (Experiment 1) or differences in oocyte quality (Experiments 2 and 3). In Experiment 1, oocytes recovered from slaughterhouse ovaries were matured in vitro for 18, 20, 24, 28 or 30 h prior to fertilization and were then cultured in vitro. In Experiment 2, Belclare (n = 69) and Suffolk (n = 71) ewes were laparoscopically inseminated using frozen-thawed semen. Presumptive zygotes were recovered between 23 and 47 h post-insemination and cultured in vitro (grouped by breed). In Experiment 3, immature oocytes from Suffolk and Belclare ewes, were matured, fertilized and cultured in vitro (grouped by breed). Cleavage rate and blastocyst development was assessed. There was no effect of time of fertilization on cleavage rate, however, a lower proportion of cleaved oocytes reached the blastocyst stage after insemination at 30h compared to 24 h (P < 0.001). Ewe breed did not affect cleavage rate of oocytes matured and fertilized in vivo (41+/-9.6 and 47+/-10.1) or in vitro (47+/-9.4 and 52+/-9.4) for Belclare and Suffolk ewes, respectively (P > 0.05; %+/-S.E.). Likewise, ewe breed had no effect on the percentage (+/-S.E.) of cleaved oocytes developing to the blastocyst stage for in vivo (29+/-7.2 and 25+/-7.9) or in vitro matured and fertilized oocytes (29+/-6.1 and 36+/-5.9) from Belclare and Suffolk ewes, respectively (P>0.05). Based on this study oocyte quality does not differ between the breeds and in addition a 4h difference in the timing of fertilization, reflective of the breed difference in the timing of the LH surge in vivo, would not affect early embryo development.
Collections Ireland -> University College Dublin -> PubMed

Full list of authors on original publication

A.C.O. Evans, P. Lonergan, A Donovan, P. Duffy, C M O' Meara, F Ward, J P Hanrahan, S Fair

Experts in our system

A.C.O. Evans
University College Dublin
Total Publications: 92
P. Lonergan
University College Dublin
Total Publications: 190
P. Duffy
University College Dublin
Total Publications: 42
J P Hanrahan
Total Publications: 58
Seán Fair
University of Limerick
Total Publications: 54