Abstract
The influence of light intensity on the rate of lay and oviposition rhythm in Japanese quail (Coturnix coturnix japonica) was investigated under 14L:10D and continuous lighting. One hundred and fourty-four laying hens aged twenty weeks were divided into four groups; the two groups (1 L-H and 14L-L) were kept under 14L:10D (light-on, 5:00, light-off, 19:00) and the other two groups (24L-H and 24L-L) were under continuous lighting. Total experimental duration was 8 weeks. During the first 4 weeks, the middle intensity was set at 69-104 lux for all groups. During the 2nd period, the high intensity was set at 2055-2152 lux for 14 L-H and 24L-H group and the low intensity was set at 2-3 lux for 14L-L and 24L-L group. The rate of lay and oviposition rhythm of each individual hen were examined for the first and the 2nd experimental period.
At the period of middle intensity, rates of lay were 89-90% under 14L:10D and 82-88% under continuous lighting. After changing the intensity to the high, rate of lay in 14L-H increased by 4% (P<0.05)and rate of lay under the low in 14L-L decreased by 24% (P<0.01), and hens paused oviposition and molting appeared in succession 10-14 days after the changing. Under continuous lighting, however, changing had no effect on the rate of lay. It was obviously recognized that the influence of the intensity on the egg production of coturnix differed by photoperiod. The treatment of high intensity under 14L:10D shortened the oviposition interval and concentrated the oviposition time in the period of the latter half of lighting (14L-H). On the other hand, the low intensity prolonged the interval and dispersed the oviposition time (14L-L). From these results, we concluded that the high intensity might increase the degree of entrainment of oviposition rhythm to photoperiod and the low intensity might affect reversely on the rhythm under 14L:10D. At the period of the middle intensity under continuous lighting, oviposition rhythm did not show an entrained rhythm to daily cycle, but a free-running one. The free-running period (FRP) of those were 26.2-26.7hr. Under the high and the low intensity of continuous lighting, FRP became prolonged and shortened, respectively. These results suggested that the oviposition rhythm of Japanese quail did not fit to "Ashoff's rule" and differed from a common biological rhythm.
