Influence of short-term fasting during the luteal phase of the estrous cycle on ovarian follicular development during the ensuing proestrus of ewes


Alexander B. M., Kiyma Z., McFarland M., Van Kirk E. A., Hallford D. M., Hawkins D. E., ...More

ANIMAL REPRODUCTION SCIENCE, vol.97, pp.356-363, 2007 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 97
  • Publication Date: 2007
  • Doi Number: 10.1016/j.anireprosci.2006.01.012
  • Journal Name: ANIMAL REPRODUCTION SCIENCE
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.356-363
  • Keywords: fasting, follicles, pituitary, sheep, estradiol, GROWTH-FACTOR-I, STIMULATING-HORMONE, LUTEINIZING-HORMONE, FEED RESTRICTION, BEEF HEIFERS, SECRETION, GONADOTROPIN, NUTRITION, PROGESTERONE, FOLLICLES
  • Eskisehir Osmangazi University Affiliated: No

Abstract

Short-term fasting of mature ewes during diestrus results in increased serum concentrations of progesterone and a delayed pre-ovulatory surge release of LH. To determine if these changes in reproductive hormones influence subsequent follicular development, mature ewes observed in estrus were assigned randomly to control (n=10) or fasted (n=15) groups. Control ewes had ad libitium access to feed, whereas fasted ewes were not fed from day 7 through 11 of their estrous cycle. Daily blood samples were collected from control and fasted ewes throughout the fasting period. Fasting increased (P < 0.001) serum concentrations of progesterone (4.4 ng/mL versus 2.7 ng/mL [+/- 0.3]). On day 12, all ewes were treated with 10 mg of PGF(2 alpha) and fasted ewes were returned to ad libitum feed. Ovaries were collected from ewes (n = 5 each group) at 0 and 72h following PGF2a in control and 0, 72 and 96 h in fasted ewes. Ovaries were weighed and small (<= 2 mm), medium (3-4 mm), and large (>= 5 mm) follicles were enumerated. Total numbers of follicles were less (P < 0.001) in fasted than fed ewes (74.6 versus 30.2 [2.2]) at Oh, but did not differ (P=0.9) when numbers of follicles were compared at similar times before the anticipated LH surge (i.e., at 72 h versus 96 h in control and fasted ewes, respectively). Within follicular size class, numbers of small and medium follicles were decreased (P=0.04) at 0 h in fasted ewes. Numbers of large follicles did not differ (P=1.0) between groups. Although numbers of small and medium ovarian follicles in fasted ewes recovered by 96 h to values comparable to fed ewes at 72 h following PGF(2 alpha), serum concentrations of estradiol 17 beta (P=0.08) and FSH (P=0.06) tended to be decreased in fasted ewes before the anticipated surge release of LH. Pituitary content of LH and FSH also tended to be lower (P <= 0.09) at 96 h in fasted ewes than at 72 h in control ewes, but did not differ (P >= 0.4) at hour 0 following PGF(2 alpha). Hypothalamic and stalk median eminence contents of GnRH were not influenced (P >= 0.2) by fasting at any time period. Fasting during the luteal phase perturbs gonadotropin secretion and may influence fertility by causing a delay in ovarian follicle development. (c) 2006 Elsevier B.V All rights reserved.