Luteinizing hormone release after administration of the gonadotropin-releasing hormone agonist Fertilan (goserelin) for synchronization of ovulation in pigs

K. P. Brüssow, F. Schneider, A. Tuchscherer, J. Rátky, R. R. Kraeling, W. Kanitz

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Abstract

The generic GnRH agonist, Fertilan (goserelin), was tested for the ability to induce an LH surge and ovulation in estrus-synchronized gilts. Three experiments were performed to 1) examine the effect of various doses of Fertilan on secretion of LH in barrows, to select doses to investigate in gilts (Exp. 1); 2) determine doses of Fertilan that would induce a preovulatory-like rise of LH in gilts (Exp. 2); and 3) determine the time of ovulation after Fertilan treatment (Exp. 3). In Exp. 1, 10 barrows were injected on d 1, 4, 7, 10, and 13 with 10,20, or 40 μg of Fertilan; 50 μg of Gonavet (depherelin; GnRH control) or saline (negative control); and sequential blood samples were collected for 480 min. There was a dose-dependent stimulation (P < 0.05) of LH release. Maximal plasma concentrations of LH (LHMAX) were 2.1 ± 0.2, 4.1 ± 0.3, 2.6 ± 0.4, and 3.4 ± 0.3 ng/mL after 10, 20, and 40 μg of Fertilan and 50 (o,g of Gonavet, respectively, and duration of release was 78 ± 9,177 ± 12, 138 ± 7, and 180 ± 11 min, respectively. Fertilan doses of 10 and 20 μg were deemed to be the most suitable for testing in gilts. In Exp. 2, 12 gilts received (after estrus synchronization with Regumate and eCG) injections of 10 or 20 μg of Fertilan or 50 μg of Gonavet 80 h after eCG to stimulate a preovulatory-like LH surge and ovulation. An LH surge was induced in 3 of the 4 gilts in both of the Fertilan groups and in all of the Gonavet-treated gilts. Characteristics of induced release of LH did not differ among groups: LHMAX, 5.0 ± 0.9 vs. 4.6 ± 1.8 vs. 6.6 ± 1.1 ng/mL; duration, 11.7 ± 2.0 vs. 12.3 ± 2.2 vs. 14.3 ± 0.5 h; interval from GnRH injection to LHMAX 4.0 ± 2.0 vs. 6.7 ± 1.3 vs. 5.8 ± 1.6 h. In Exp. 3, estrus-synchronized gilts were injected with 20 μg of Fertilan (n = 8) or 50 μg of Gonavet (n = 4), and the time of ovulation was determined by repeated endoscopic examination. Time of ovulation ranged from 34 to 42 h postGnRH; however, ovulation occurred earlier in the Gonavet compared with the other groups (P < 0.05). Results of these experiments indicate that 1) barrows are an appropriate model for determining GnRH doses that can be effective in inducing a preovulatory-like LH surge in females; 2) the generic GnRH agonist Fertilan, at doses of 10 to 20 μg, can stimulate an LH surge in gilts, with subsequent ovulation; and 3) Fertilan at doses of 10 and 20 μg should be examined further for use in fixed-time insemination protocols.

Original languageEnglish
Pages (from-to)129-137
Number of pages9
JournalJournal of Animal Science
Volume85
Issue number1
DOIs
Publication statusPublished - Jan 1 2007

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Keywords

  • Gonadotropin-releasing hormone agonist
  • Luteinizing hormone
  • Ovulation
  • Pig

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

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