HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Brüssow, K.-P. Articles by Kanitz, W. Search for Related Content PubMed PubMed Citation Articles by Brüssow, K.-P. Articles by Kanitz, W.

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

K.-P. Brüssow^*,1, F. Schneider^*, A. Tuchscherer^*, J. Rátky, R. R. Kraeling and W. Kanitz^*

^* FBN Research Institute for the Biology of Farm Animals, 18196 Dummerstorf, Germany; and Research Institute for Animal Breeding and Nutrition, 2053 Herceghalom, Hungary; and and L&R Research Associates, 30677 Watkinsville, GA

¹ Corresponding author: bruessow{at}fbn-dummerstorf.de

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 (LH_MAX) 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 µg 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: LH_MAX, 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 LH_MAX, 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.

Key Words: gonadotropin-releasing hormone agonist • luteinizing hormone • ovulation • pig