HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Spicer, L. J. Articles by Tucker, H. A. Search for Related Content PubMed PubMed Citation Articles by Spicer, L. J. Articles by Tucker, H. A.

Anovulation in Postpartum Suckled Beef Cows. I. Associations among Size and Numbers of Ovarian Follicles, Uterine Involution, and Hormones in Serum and Follicular Fluid^1,2,

Michigan State University^,9, East Lansing 48824 and U.S. Department of Agriculture^,7, Miles City, MT 59301

Abstract

Changes in sizes and numbers of ovarian antral follicles, uterine size and weight, serum hormones, and frequency and duration of suckling were examined during the postpartum anovulatory period in primiparous, suckled beef cows. Twenty-one anovulatory, suckled cows (n=4 to 6/d) were slaughtered on d 7, 14, 28 and 42 to 56 after parturition. In addition, a total of 11 postpartum cows that had begun cyclic activity were slaughtered on d 28, 42 or 56. Blood was collected at 10-min intervals for 6 h 1 d before slaughter for measurement of prolactin, Cortisol and progesterone in serum. Numbers of medium (4.0 to 7.9 mm) follicles increased fourfold (P<.05) between d 7 and 42 to 56 in anovulatory cows, whereas numbers of small (1.0 to 3.9 mm) and large (8.0 mm) follicles did not change (P>.10). Uterine involution was complete by d 28. In anovulatory cows, a higher (P<.05) proportion of largest (but not second-largest) follicles was opposite the ovary containing the corpus albicans from pregnancy (CAP). In addition, 90% of these largest follicles opposite the CAP had concentrations of estradiol greater than progesterone. In cyclic cows, however, first ovulations occurred with equal frequency on either ovary. Concentrations of prolactin or Cortisol in serum or duration of suckling were not associated with changes in uterine or ovarian measurements.

In conclusion, growth and function of the largest (but not second-largest) follicle were reduced when located on the ovary containing the CAP. We suggest that increased numbers of mediumsized follicles may provide a pool from which ovulatory follicles are selected, as one of the necessary steps leading to first postpartum ovulation.

¹ Michigan Agr. Exp. Sta. Journal Article No. 11594. This research was supported in part by a grant from The Upjohn Company.

² We thank Lisa Ritchie and Steven Lyth for expert technical assistance.

³ M. S. Hershey Med. Center, Pennsylvania State Univ., Hershey, PA 17033.

⁴ Reprod. Endocrinol. Program, Univ. of Michigan, Ann Arbor, MI 48109.

⁵ Merck, Sharp and Dohme Res. Lab., Merck and Co., Inc., Rahway, NJ 07065.

⁶ 4444 S. Hagadorn, Okemos, MI 48864.

⁷ LARRS, Miles City, MT 59301.

⁸ Reprint requests.

⁹ Dept. of Anim. Sci.

This article has been cited by other articles:

				L. J Spicer, P. Y Aad, D. T Allen, S. Mazerbourg, A. H Payne, and A. J Hsueh Growth Differentiation Factor 9 (GDF9) Stimulates Proliferation and Inhibits Steroidogenesis by Bovine Theca Cells: Influence of Follicle Size on Responses to GDF9 Biol Reprod, February 1, 2008; 78(2): 243 - 253. [Abstract] [Full Text] [PDF]