Reproduction Abstracts

Successful pregnancy depends on a succession of complex biological processes that are regulated temporally and spatially. In term of contribution to pregnancy, the mother not only produces oocytes but she also hosts the whole gestation, mainly in the uterus. For decades, a major focus has been made on oocyte and embryo quality in term of contribution to progression and issue of pregnancy in mammals, including cattle. Nevertheless, in the bovine species, recent studies have clearly established the impact of uterus quality on pregnancy issue as early as interactions with the conceptus take place. In dairy and meat cattle, persistent or transient modifications in organisation and functionality of the endometrium before and during reproductive life (e. g. nutrition, infections) can dramatically affect pre-implantation embryo trajectory through epigenetic alterations, with lasting consequences on subsequent progression of pregnancy as well as post-natal health. In addition to this driving property of the endometrium, distinct endometrial responses can also be elicited by bovine embryos presenting distinct post-implantation fates, e.g. when they are generated by artificial insemination, IVF or by somatic cell nuclear transfer. Molecular and cellular data will be presented as illustrations of the driver-sensor properties of the bovine endometrium. Evaluation of endometrial quality and restoration of the endometrial physiology to a level compatible with term pregnancy represent two ways that can be used to increase fertility in cattle, provided that applied treatments are devoid of detrimental effects on expression of production traits in adult.