✦ LIBER ✦

Annual cycle of plasma luteinizing hormone concentrations in wild mallard drakes

✍ Scribed by Haase, E. ;Sharp, P. J. ;Paulke, E.

Publisher: John Wiley and Sons
Year: 1975
Tongue: English
Weight: 252 KB
Volume: 194
Category: Article
ISSN: 0022-104X
DOI: 10.1002/jez.1401940312

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✦ Synopsis

Abstract

Plasma LH concentrations were followed in 9 individually marked wild mallard drakes in Kiel (54°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 regression 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.

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