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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #322272
Title: Reproductive Management for Optimal Oocyte Development to Enhance Fertility

Author
item Geary, Thomas
item ABREU, FERNANDA - The Ohio State University

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2015
Publication Date: 3/19/2015
Citation: Geary, T.W., Abreu, F.M. 2015. Reproductive Management for Optimal Oocyte Development to Enhance Fertility. 19th Conference on New Techniques in Bovine Production and Reproduction. Brazil. CD:26-39.

Interpretive Summary: There are multiple steps associated with release of a fertile egg. The egg develops within a follicle on the ovary in preparation for its release. More than 99% of eggs never develop to the point of release (ovulation). The few eggs that do reach ovulation grow within follicles called ovulatory follicles. Hormones can be used to induce ovulation. When ovulation is induced, it is critical that the egg is matured properly. The follicle must grow so that it produces estrogen at the time of ovulation. Estrogen prepares the egg for fertilization. It also prepares cells of the follicle to produce progesterone. A simple measure of estrogen production is to measure the size of the follicle. Large follicles are known for producing more estrogen. Thus, large follicles contain an egg that is more mature and ready for ovulation.

Technical Abstract: There are multiple steps associated with the ovulatory follicle that affect oocyte growth, fertilization, embryo development and establishment of pregnancy. When estrous cycles are manipulated with assisted reproductive technologies and ovulation induced, some of these variables become more important. Length of proestrus (interval from induced luteolysis to induced ovulation), ovulatory follicle growth rate and size are factors that affect the maturation of the follicle and oocyte at induced ovulation. Perhaps the critical maturational component is the production of sufficient estradiol by the ovulatory follicle to prepare follicular cells for luteinization and subsequent progesterone synthesis and prepare the uterus for pregnancy. The exact roles of estradiol in oocyte maturation remain unclear. When length of proestrus is held constant, perhaps the most practical follicular measure of fertility is ovulatory follicle size because it is an easily measured attribute of the follicle that is highly associated with its ability to produce estradiol.