Photoperiodic requirement for the dissipation of scotorefractoriness in Japanese quail.

Male Japanese quail were reared on short days (6L:18D) and at 15-20 weeks of age those which had become sexually mature (i.e., scotorefractory) were transferred to long days (18L:6D) for between 2 and 29 weeks. The birds were then returned to 6L:18D for 3 weeks to test for the dissipation of scotorefractoriness. This was assessed by a decrease in at least 3 of 4 indices of reproductive function: testicular weight, area of the cloacal gland, and levels of plasma LH and testosterone. There was great individual variation in the photoperiodic requirement for the dissipation of scotorefractoriness, ranging between 6 and 29 weeks of exposure to long days. Scotorefractoriness was dissipated in about 50% of the birds after exposure to long days for between 6 and 12 weeks. It is concluded that the photoperiodic requirement for the dissipation of scotorefractoriness in quail cannot be defined precisely.