Dynamics of Gonadotropin Release Following Ovariectomy and Injection of Gonadotropin-Releasing Hormone in Early Postpartum Dairy Cows

G. A. Dissen, T. A. Mollett, R. S. Youngquist, H. A. Garverick

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    1 Scopus citations

    Abstract

    The influence of the ovary and of injection of low doses of gonadotropin-releasing hormone on secretion and gonadotropin-releasing hormone-induced release of gonadotropins in early postpartum cows was examined in a 2 × 2 factorial design (6 cows/group). Twelve cows were ovariectomized 2 d postpartum (calving = d 0; groups 1 and 2) and 12 cows were left intact (groups 3 and 4). Groups 1 and 3 gonadotropin-releasing hormone (5 μg) every 120 min for 70 h from d 6 to d 9; groups 2 and 4 saline by the same regimen. All animals 50 μg gonadotropin-releasing hormone on d 9. Mean concentrations of FSH were higher following ovariectomy compared with those of intact cows 6 to 8 d postpartum, whereas no differences in FSH were observed between cows receiving gonadotropin-releasing hormone or saline during this period. Concentrations of LH were similar in intact and ovariectomized cows on d 6 to 8 but were increased in cows receiving gonadotropin-releasing hormone compared with cows receiving saline. Ovariectomy did not alter the gonadotropin-releasing hormone-induced release of gonadotropins on d 9. Injection of gonadotropin-releasing hormone on d 6 to 8 resulted in a decreased gonadotropin-releasing hormone-induced release of gonadotropins on d 9. It was concluded that removal of ovarian influence resulted in increased secretion of FSH but did not affect gonadotropin-releasing hormone-induced release of LH and FSH during the early postpartum period.

    Original languageEnglish (US)
    Pages (from-to)3489-3496
    Number of pages8
    JournalJournal of dairy science
    Volume71
    Issue number12
    DOIs
    StatePublished - Jan 1 1988

    ASJC Scopus subject areas

    • Food Science
    • Animal Science and Zoology
    • Genetics

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