Egg laying and ovarian follicular growth in Japanese quail under continuous lighting.

摘要

Egg laying and the pattern of ovarian follicle growth were compared between the conditions of 14 h light:10 h darkness (14L:10D) and continuous light (LL). Laying quails at 15 weeks of age were kept firstly under 14L:10D and secondly under LL, eachfor 7 weeks. Oviposition times were recorded throughout the experimental period. To examine the pattern of follicle growth, 3 kinds of fat-soluble dye were given orally once daily at a fixed time for 7 weeks under each condition. Ovipositions under 14L:10D were concentrated within the period from 8 h after the onset of the light period to 2 h after the onset of darkness, with a peak 11-12 h after the onset of the light period. Ovipositions under 14L:10D showed a high entrainment to the light-dark cycle.On the other hand, ovipositions under LL were found uniformly throughout the 24-h period. The oviposition interval between eggs within a clutch was 24.70?.07 (mean馭EM) h under 14L:10D and 26.83?.05 h under LL. The interval increased significantly ontransfer to LL. Quails under LL produced fewer relatively small clutches (1-6 eggs) and more large clutches (>10 eggs) compared with birds under 14L:10D. On transfer from 14L:10D to LL there were significant increases in the length of the period of rapidfollicle growth and yolk volume at the time of ovulation. However, no significant change was found in the number of growing follicles in the ovary and the total amount of yolk deposited per day under either condition.