[Disjunction between the daily duration of light and the plasma level of prolactin under hyperlong days in rams].
Adult rams were submitted to an artificial light regime with increasing and decreasing daylengths between 6 and 20 hrs. over a period of 8 months. Blood samples occurred at different durations of daylengths for measuring plasma levels of prolactin. Levels were high for a daily duration of light of 14.20, 17 and 18.30 hrs. along the increasing light-phase and of 18.30 hrs. during the decreasing light-phase. On the other hand prolactin levels were low for short daylengths, but also for a daylength of 20 hrs. It clearly appears that hyperlong days (greater than 18 hrs.) do not stimulate (or do actively inhibit) the secretion of prolactin in ovines.
D000818:Animals; D008027:Light; D008297:Male; D010507:Periodicity; D011388:Prolactin / Q000097:blood*; D012756:Sheep / Q000097:blood*
D011388:Prolactin
Disjonction entre la durée quotidienne d'éclairement et le taux plasmatique de prolactine pour les jours hyperlongs chez les ovins.