Evaluation of testosterone response to intramuscular injection of GnRH and its correlation with sperm quality...

Eight 40-week-old New Hampshire cockerels (average liveweight: 3.10 +/- 0.2 kg) were used for studying the testosterone response to a single intramuscular dose (5 micrograms/kg b.w.) of exogenous 6D-Phe gonadotropin releasing hormone (GnRH). Serum samples were collected at 15-min intervals during the first hour and at half-hour intervals up to two hours post injection. The semen samples were collected 24 h before GnRH treatment. Testosterone peaks were found 45 to 60 min after the treatment. The coefficient of correlation between the semen quality parameters and the testosterone response to GnRH was evaluated both by Rank correlation and by multiple regression analyses. Rank correlation showed moderate but not significant values while multiple regression analyses showed a close correlation (multiple R = 0.72). The results show that testosterone response to GnRH may be used as a marker of semen quality in cockerels.