Abstract
In order to find the better lighting technique than a light-dark rhythm reported by the author previoudly, in this study the egg production by the light-dark rhythm as contral groups and that by other 2 lighting regimes (test groups) was compared. In the control groups, 5 light time (L)-dark time (D) systems abbreviated as 12L-12D, 14L-10D, 16L-8D, 18L-6D, and 20L-4D were used. One of the test groups was L-D-L-D rhythm system, in which 2 hours of the same light time as the control was brighted at the mid dark time, and they were shown as 12L-5D-2L-5D, 14L-4D-2L-4D, 16L-3D-2L-3D and 18L-2D-2L-2D. The other of the test groups was the gradual increase system, in which the lighting was restricted to 12 or 14 hours per day for the first 4 weeks, then the lighting increased by 15 minutes per week, finally making up to 20 hours of light time, and after that the light time of 20 hours was maintained; they were shown as 12L+15min. L/wk, and 14L+15min. L/wk. Experiments were conducted by 2 repetitions. In each repetition, 748 femal quail of 45-day-old were allotted to 11 groups and each group was further divided into 4 lots for 4 feeding cages, placed in a light-shielding and air-conditioning apparatus. The light intensity was maintained by an electric bulb with red calor and about 4 luxes at the front of the middle portion of the feeding cages in the apparatus. The egg production of quail by each lighting regime was examined at intervals of 4 weeks during 48 weeks. The results obtained were as follows:
1) In the control group, it was shown that by a variance analysis only the viability of the quail was decreased with lengthening of light time from 12L to 20L. But the other egg production characteristics were increased with the same conditions.
2) As the result of comparison of the egg production by the same light time between control group (L-D rhythm) and L-D-L-D rhythm of test groups, it was found that the production in the latter was superior than that in the former.
3) In the restricted and then the gradual increased lighting, the production was made better progressively with increasing the light time. But the production of a 48 weeks period did not attained to that of 20L-4D and 18L-2D-2L-2D.
