No abstract

). Plasma prolactin concentrations remained suppressed ( < 20 ng/ml) for the duration of melatonin-feeding (Groups CL/M and NL/M) whereas control values (Group C) were elevated (20\p=n-\120ng/ml) between April and August (P < 0\m=.\05).The ovarian response by hinds to melatonin therefore depends on initial reproductive status and recent photoperiodic history, and continued administration to cyclic hinds stimulates prolonged ovarian cyclicity irrespective of the time of year.