EVALUATING THE ROLE OF ESTRADIOL DURING THE PRE-OVULATORY PERIOD ON FERTILITY IN BEEF CATTLE
Livestock and Range Research Laboratory (LARRL)
2013 Annual Report
1a.Objectives (from AD-416):
To improve our understanding of the mechanism(s) by which pre-ovulatory estradiol concentration and a prolonged pro-estrus affect embryo development and pregnancy establishment in beef cattle.
1b.Approach (from AD-416):
Mechanisms controlling fertility of single matings in beef cattle are poorly understood, especially cows that exhibit estrus. The scientists involved with this agreement from both institutions will share data and research efforts to identify mechanisms controlling fertility and their effects on early embryo development, pregnancy establishment and maintenance. This research will include evaluation of serum estradiol and luteinizing hormone collected from cows around the time of ovulation and the role of these hormones on oocyte maturation, fertilization, early embryo development, and the ability of differentially developed oocytes to establish viable pregnancies. The USDA-ARS, Fort Keogh, Miles City, MT, has a majority of the cattle used for these studies, and the research involved with these studies will occur at Fort Keogh.
One manuscript was published in and two additional manuscripts have been returned by Jounal of Animal Science with requests for revisions. The published manuscript is entitled, “Preovulatory estradiol and the establishment and maintenance of pregnancy in suckled beef cows”. The two submitted manuscripts are entitled, “The effect of follicle age on pregnancy rate in beef heifers” and “The effect of follicle age on pregnancy rate in beef cows”. In addition, Mike Day, collaborator at The Ohio State University visited Fort Keogh in June of this year and he and a co-mentored graduate student participated in a breeding project this year in the Physiology Cow Herd. This graduate student also presented results from a study conducted last year within this collaboration at the 2013 American Society of Animal Sciences Annual Meeting held in Indianapolis.