Haase E, Sharp P J, Paulke E
J Exp Zool. 1975 Dec;194(3):553-8. doi: 10.1002/jez.1401940312.
Plasma LH concentrations were followed in 9 individually marked wild mallard drakes in Kiel (54 degrees N) for one year at monthly intervals. Mean LH levels increased during the spring and reached the annual maximum in April and May. In June when testicular regressions occurs, the LH titer sharply decreased and was lower than at any other phase of the annual cycle. In late fall mean plasma LH concentrations increased and, whilst not reaching the values observed during the breeding season, remained relatively high during the winter. Thus, in the mallard LH can be released under short and long daily photo-periods.
对基尔（北纬54度）9只单独标记的野生绿头雄鸭的血浆促黄体生成素（LH）浓度进行了为期一年的跟踪，每月测量一次。春季期间，促黄体生成素的平均水平上升，并在4月和5月达到年度最高值。6月睾丸开始退化时，促黄体生成素滴度急剧下降，低于年度周期的任何其他阶段。在深秋，血浆促黄体生成素的平均浓度上升，虽然未达到繁殖季节观察到的值，但在冬季仍相对较高。因此，在绿头鸭中，促黄体生成素可在短日照和长日照条件下释放。
