Location: Range and Livestock ResearchTitle: Influence of follicle characteristics at ovulation on early embryo survival Author
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2012
Publication Date: 7/16/2012
Citation: Geary, T.W., Smith, M.F., Macneil, M.D., Day, M.L., Bridges, G.A., Perry, G.A., Abreu, F.M., Atkins, J.A., Pohler, K.G., Jinks, E.M., Roberts, C.A. 2012. Influence of follicle characteristics at ovulation on early embryo survival. Western Section of Animal Science Proceedings. 90(Suppl. 3):5. Abstract No. 12. Interpretive Summary:
Technical Abstract: Reproductive losses are significant in domestic animals and represent huge economic inefficiencies in livestock production. Across livestock species, embryonic mortality is the greatest contributor to reproductive losses. In most livestock species, early pregnancy diagnosis is an impediment to making significant progress to alleviate these losses. Perhaps unfairly, the female of each livestock species receives the blame for the majority of pregnancy failures. Research has focused on production of an optimal follicle that leads to ovulation of a highly fertile oocyte and production of steroids responsible for preparation of the female reproductive tract for pregnancy. Most studies have used hormonal manipulation of the estrous cycle and ovulation to identify factors affecting pregnancy success. Physiological maturity of the ovulatory follicle includes numerous reproductive processes and events obligatory for pregnancy establishment and maintenance. In the sow, mare, beef and dairy cow, oocytes derived from larger follicles were more competent, as assessed by in vitro development, than oocytes from smaller follicles. In cattle, ovulatory follicle size was highly correlated with serum estradiol concentration and estradiol supplementation at AI improved pregnancy rates of cows ovulating smaller follicles. Greater ovulatory follicle size and more rapidly growing follicles at GnRH-induced ovulation were positively associated with fertilization success, while ovulatory follicle size, but not follicle growth rate was positively associated with recovery of a viable embryo on day 7 in beef cows. In the mare, age related changes in follicular signaling appear to play a large role in oocyte quality and fertility. This symposium focuses on follicular characteristics involved in early embryo survival, including follicle/oocyte maturation as affected by ovulatory follicle age, size, hormonal environment, etc., and their effects on pregnancy establishment and maintenance. There is a strong relationship between the ovulatory follicle and steroid production related to early embryo development and pregnancy establishment.