Development of persistent ovarian follicles during synchronization of estrus influences the superovulatory response to FSH treatment in cattle

M. E. Wehrman, K. E. Fike, F. N. Kojima, E. G. Bergfeld, A. S. Cupp, V. Mariscal, T. Sanchez, I. E. Kinder

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The synchronization of estrus with synthetic progestins or progesterone (P4) results in the development of a large, persistent ovarian follicle. The objectives of the present study were to determine if development of a persistent ovarian follicle during synchronization of estrus suppresses recruitment of additional follicles during FSH treatment. On Day 5 of the estrous cycle (estrus=Day 0), beef cows were treated with 0.5 or 2.0 P4 releasing intravaginal devices (PRIDs) for 8 d (Experiment 1, n=20), 5 or 2 d (Experiment 2, n=44) before initiation of FSH treatment. Prostaglandin F (25 mg) was administered on Days 5 and 6. Superovulation was induced with 24 mg of recombinant bovine FSH (rbFSH, Experiment 1) or 28 mg of FSH-P (Experiment 2) over a 3- or 4-d period, respectively. The PRIDs were removed concurrently with the 5th injection of rbFSH or FSH-P. There was a treatment-by-day interaction (P<0.001) for the concentration of 17ß-estradiol in cows treated for 8, 5 or 2 d before FSH treatment. In Experiment 1, FSH treatment initiated 8 d after insertion of a 0.5 PRID did not affect the number of CL (6.9±1.4 vs 6.7±1.6), ova/embryos (3.7±1.3 vs 3.0±1.3) and transferable embryos (2.4±0.9 vs 3.0±0.9) compared with that of the 2.0 PRIDs. In Experiment 2, FSH treatment initiated 5 d after insertion of a 0.5 PRID decreased the number of CL (4.0±0.5 vs 8.3±0.8; P<0.001), ova/embryos (3.0±0.6 vs 5.9±1.2; P<0.03) and transferable embryos (2.3±0.6 vs 5.1±1.0; P<0.03) compared with that of a 2.0 PRID, respectively. Initiation of FSH treatment 2 d after insertion of a 0.5 PRID compared with a 2.0 PRID had no affect on the number of CL (8.0±2.1 vs 8.7±1.2), total ova (4.8±1.4 vs 6.9±1.4) and transferable embryos (2.9±1.2 vs 6.1±1.7). In conclusion, treatment with low doses of P4 (0.5 PRID) for 5 d but not for 2 or 8 d before initiation of FSH treatment results in the development of a dominant ovarian follicle, which reduces recruitment of ovarian follicles, and the number of CL, total ova and transferable embryos.

Original languageEnglish (US)
Pages (from-to)593-610
Number of pages18
JournalTheriogenology
Volume45
Issue number3
DOIs
StatePublished - 1996

Keywords

  • Bovine
  • Ovarian follicular development
  • Progesterone
  • Superovulation

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology
  • Equine

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