Effect of Short-Day or Low-Intensity Light Treatments on Reproduction of Fall-Hatched Turkeys in Two Environments

THE favorable effect of light restriction during the late growing period on subsequent reproduction of female turkeys hatched in the months of October through February was demonstrated by Harper and Parker (1957, 1960, 1962) and McCartney et al. (1961). Leighton and Shoffner (1961) and Marr et al. (1956) reported that turkey hens hatched in March were benefited by light preconditioning only slightly while those hatched in May and September showed no beneficial effect according to the latter authors. The methods of light restriction used in the various experiments consisted of exposing the turkeys to short days of 3 to 10 hours each over periods of 1 to 14 weeks starting at 14 to 27 weeks and prior to the application of stimulatory light. Wilson et al. (1962) found daily continuous photoperiods of 6 or 8 hours superior to those of 3, 4, or 10 hours and the longer restriction periods…