Journal of Animal Science, Vol 74, Issue 12 2985-2991, Copyright © 1996 by American Society of Animal Science

JOURNAL ARTICLE

Exogenous pulses of luteinizing hormone cause persistence of the largest bovine ovarian follicle

R. Taft, N. Ahmad and E. K. Inskeep
Division of Animal and Veterinary Sciences, West Virginia University, Morgantown 26506-6108, USA.

The objectives of this study were, 1) to determine whether increased frequency of LH pulses, independent of changes in progesterone, will cause persistence of the first largest ovarian follicle (LF1) during the bovine estrous cycle and 2) to determine whether a follicle produced in this manner will ovulate after luteal regression. In Exp. 1, 32 nonlactating beef cows were randomized into four groups. Bovine LH was given as 50 micrograms i.v. every 2 h from 0800 on d 7 through 0800 on d 13 postestrus to cows in two groups, which in addition either received PGF2 alpha on d 12 and were allowed to ovulate (LHOV; Group 1) or were ovariectomized (LHOVX; Group 2) on d 13. Cows in Group 3 received progesterone via a used controlled internal drug releasing device (CIDR) on d 4 to 13, PGF2 alpha on d 6, and ovariectomy on d 13. These cows received 1 mL of saline i.v. every 2 h on d 7 to 13, as did those in Group 4 (SAL), but cows in Group 4 did not receive any PGF2 alpha. Proportion (percentage) of LF1 maintained until d 13 was similar in cows with CIDR (100) and on LH (88) but less in cows on SAL (36; P < .01). The LF1 were largest in cows with CIDR, smallest in cows on SAL, and intermediate in cows on LH (P < .001). During d 7 to 13, progesterone was lesser and estradiol was greater in peripheral plasma in cows with CIDR than in cows on LH or SAL (P < .001). In Experiment 2, beef heifers received 50 micrograms of bLH (LH; n = 5) or saline (SAL; n = 4) i.v. every 2 h from 0800 on d 7 until 12 h after signs of estrus were observed following PGF2 alpha on d 12. The LF1 were maintained by LH and 60% ovulated; all LF1 were replaced during treatment in heifers on SAL. The LF1 were larger in heifers on LH, but estradiol and progesterone did not differ between groups. In conclusion, an increased frequency of LH pulses during a normal luteal phase allowed LF1 to persist but did not increase secretion of estradiol.

This article has been cited by other articles:

				M. Mihm, P.J. Baker, J.L.H. Ireland, G.W. Smith, P.M. Coussens, A.C.O. Evans, and J.J. Ireland Molecular Evidence That Growth of Dominant Follicles Involves a Reduction in Follicle-Stimulating Hormone Dependence and an Increase in Luteinizing Hormone Dependence in Cattle Biol Reprod, June 1, 2006; 74(6): 1051 - 1059. [Abstract] [Full Text] [PDF]

				M. Manikkam, T. L. Steckler, K. B. Welch, E. K. Inskeep, and V. Padmanabhan Fetal Programming: Prenatal Testosterone Treatment Leads to Follicular Persistence/Luteal Defects; Partial Restoration of Ovarian Function by Cyclic Progesterone Treatment Endocrinology, April 1, 2006; 147(4): 1997 - 2007. [Abstract] [Full Text] [PDF]

				C. R Burke, H. Cardenas, M. L Mussard, and M. L Day Histological and steroidogenic changes in dominant ovarian follicles during oestradiol-induced atresia in heifers Reproduction, May 1, 2005; 129(5): 611 - 620. [Abstract] [Full Text] [PDF]

				E. K. Inskeep Preovulatory, postovulatory, and postmaternal recognition effects of concentrations of progesterone on embryonic survival in the cow J Anim Sci, January 1, 2004; 82(13_suppl): E24 - 39. [Abstract] [Full Text] [PDF]

				P. M. Bartlewski, R. Duggavathi, J. Aravindakshan, D. M.W. Barrett, S. J. Cook, and N. C. Rawlings Effects of a 6-Day Treatment with Medroxyprogesterone Acetate after Prostaglandin F2{alpha}-Induced Luteolysis at Midcycle on Antral Follicular Development and Ovulation Rate in Nonprolific Western White-Faced Ewes Biol Reprod, April 1, 2003; 68(4): 1403 - 1412. [Abstract] [Full Text] [PDF]

				R. Sartori, P. M. Fricke, J. C.P. Ferreira, O.J. Ginther, and M. C. Wiltbank Follicular Deviation and Acquisition of Ovulatory Capacity in Bovine Follicles Biol Reprod, November 1, 2001; 65(5): 1403 - 1409. [Abstract] [Full Text] [PDF]

				M. D. Calder, M. Manikkam, B. E. Salfen, R. S. Youngquist, D. B. Lubahn, W. R. Lamberson, and H. Allen Garverick Dominant Bovine Ovarian Follicular Cysts Express Increased Levels of Messenger RNAs for Luteinizing Hormone Receptor and 3{beta}-Hydroxysteroid Dehydrogenase {Delta}4,{Delta}5 Isomerase Compared to Normal Dominant Follicles Biol Reprod, August 1, 2001; 65(2): 471 - 476. [Abstract] [Full Text] [PDF]