Influence of short-term fasting during the luteal phase of the estrous cycle on ovarian follicular development during the ensuing proestrus of ewes
ANIMAL REPRODUCTION SCIENCE, cilt.97, ss.356-363, 2007 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 97
- Basım Tarihi: 2007
- Doi Numarası: 10.1016/j.anireprosci.2006.01.012
- Dergi Adı: ANIMAL REPRODUCTION SCIENCE
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Sayfa Sayıları: ss.356-363
- Anahtar Kelimeler: fasting, follicles, pituitary, sheep, estradiol, GROWTH-FACTOR-I, STIMULATING-HORMONE, LUTEINIZING-HORMONE, FEED RESTRICTION, BEEF HEIFERS, SECRETION, GONADOTROPIN, NUTRITION, PROGESTERONE, FOLLICLES
- Eskişehir Osmangazi Üniversitesi Adresli: Hayır
Özet
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.