Serum Gonadotropins After Gonadotropin-Releasing Hormone Injection in Bulls Subjected to Spacial Restriction (original) (raw)

Response patterns of luteinizing hor- mone, follicle-stimulating hormone, and testosterone after injection of gonado- tropin-releasing hormone were investi- gated in bulls grouped by weight (250 to 459 kg body weight) and confined five per pen in 9.2 or 6.4 m 2 space per bull in two replicates. Blood samples were collected for lh prior to injection of 100 /zg gonadotropin releasing hormone and 5 h after injection at 15-min intervals. Overall mean luteinizing hormone con- centrations were not affected by spacial restriction or replicate. Interaction of treatment by time revealed that luteinizing hormone response curves were not similar. Restricted bulls had a higher response of luteinizing hormone to gonadrotropin-releasing hormone. Folli- cle-stimulating hormone increased in all groups within 15 min and peaked at 219.4 ng/ml at 45 min. Both gonadotropin responses returned to preinjection con- centrations by 4 h. Testosterone was affected by treatment, replicate, and time of sampling...