The influence of daylength and environment on reproduction, broodiness, and mortality of turkeys.

Abstract LENGTH OF photoperiod, or daylength, appears to be the most important but not necessarily the only feature of artificial lighting practice that can influence the reproductive response of turkeys to light stimulation. With white light derived from an incandescent source supplementing natural daylight, initial photoperiods of 13 to 15 hours are widely used in connection with morning lights in the range of 1I/2 to 5 foot-candles at bird height. The usual hour to start lights appears to be 4 a.m. local standard, or zone time, turning them off after full daylight arrives. The same starting hour is maintained, as a rule, throughout the winter-spring breeding season in the northern hemisphere. Evening lights are not generally used. Depending on the latitude, the distance from the standard time-zone meridian, and the date lighting is initiated, the 4 a.m. starting hour will produce initial photoperiods of varying length. Measured from the hour lights …