Influence of GnRH administration on timing of the LH surge and ovulation in dwarf goats

This study was conducted to determine whether or not exogenous gonadotropin releasing hormone (GnRH) alters the timing or improves the synchrony of estrus, the LH surge, and ovulation following estrous synchronization in dwarf goats, and to assess the effects of season on these parameters. In Januar...

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Bibliographic Details
Published in:Theriogenology 2003-08, Vol.60 (3), p.397-406
Main Authors: Pierson, Janice T., Baldassarre, Hernan, Keefer, Carol L., Downey, Bruce R.
Format: Article
Language:English
Subjects:
Administration, Intravaginal
Animals
Chorionic Gonadotropin - administration & dosage
cloprostenol
Cloprostenol - administration & dosage
Dwarf goats
equine chorionic gonadotropin
estrus
Estrus Detection
Estrus Synchronization
Female
GnRH
goats
Goats - physiology
gonadotropin-releasing hormone
Gonadotropin-Releasing Hormone - administration & dosage
Horses
Kinetics
laparoscopy
LH surge
luteinizing hormone
Luteinizing Hormone - blood
Luteinizing Hormone - metabolism
males
Medroxyprogesterone Acetate - administration & dosage
Nigerian Dwarf (goat breed)
Ovulation
Ovulation - drug effects
sampling
Season
Seasons
Time Factors
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Summary:This study was conducted to determine whether or not exogenous gonadotropin releasing hormone (GnRH) alters the timing or improves the synchrony of estrus, the LH surge, and ovulation following estrous synchronization in dwarf goats, and to assess the effects of season on these parameters. In January and June, estrus was synchronized in 12 Pygmy and Nigerian Dwarf goats with a 10-day progestagen sponge, 125 μg cloprostenol i.m. 48 h before sponge removal, and 300 IU equine chorionic gonadotrophin (eCG) i.m. at sponge removal. Six of the 12 goats were given 50 μg GnRH i.m. 24 h after sponge removal. Onset of estrus was monitored using two males. Samples for plasma LH were collected at 2 h intervals beginning 22 h after sponge removal and ending at 48 h in January and at 58 h in June. Time of ovulation time was confirmed by laparoscopy at 36, 50, 60, and 74 h in January and at 50, 60, and 74 h in June. Administration of GnRH had no significant effect on the onset of estrus; however, it reduced the interval from sponge removal to the LH surge and improved the synchrony of the LH surge ( P
ISSN:0093-691X
1879-3231
DOI:10.1016/S0093-691X(03)00037-2