Abstract
Twelve bull calves, 2 to 24 days of age, were assigned to two groups of six calves and administered a single 50μg intramuscular injection of gonadotropin releasing hormone. Bull calves in group 1 were 2 to 5 days of age (mean 3.0 days), and bull calves in group 2 were 10 to 24 days of age (mean 17.1 days). Blood plasma for radioimmunoassay of luteinizing hormone and testosterone was collected at .5-h intervals for 3-h and at 4- and 6-h following treatment. With increasing age, preinjection luteinizing hormone concentrations in plasma decreased while preinjection testosterone concentrations increased. Mean preinjection luteinizing hormone concentrations for group 1 (1.01±.07ng/ml; mean±standard error) were higher than for group 2 (.61±.12ng/ml). Preinjection luteinizing hormone and testosterone concentrations were correlated −.63. Following treatment, luteinizing hormone increased with mean peak concentrations of 7.28±.74 and 6.95±1.79ng/ml for groups 1 and 2. Peak testosterone response following gonadotropin releasing hormone was higher for group 2 than 1 (1077±253 versus 436±116pg/ml).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
