| Popis: |
Five studies were conducted with mature White Leghorn roosters to study variables associated with concentrations of testosterone in blood sampled from a wing vein. Testosterone in blood plasma was unchanged 15, 30, or 45 min after collection of semen artificially whether or not roosters were trained for collection of semen. Likewise, cohabitation with hens for 7 to 8 hr was without effect. However, trained roosters had higher (P Variations in concentrations of testosterone among sequential samples of blood collected at 45-min intervals for 3 hr indicated random pulsatile releases of testosterone as reported for mammals. Sequential sampling at 15 min intervals for 1 to 2 hr revealed that the testosterone increases (up to 10 ng/ml) lasted for about 1 hr and that the returns to basal concentrations required about 1 to 1.5 hr. The interval between pulsatile releases may be as long as 3 hr in some roosters. These results indicate that roosters have spontaneous and pulsatile releases of testosterone as expected, because roosters release luteinizing hormone episodically during both light and dark cycles of the day. |
