KOBAYASI Shin Dept. of Agric., Saga Univ., Assistant., 農学部, 助手 (70039337)
UTIDA Susumu Dept. of Agric., Saga Univ., Assis. Professor., 農学部, 助教授 (00038275)
OKAMOTO Satoru Dept. of Agric., Saga Univ., Professor., 農学部, 教授 (00041640)
|Budget Amount *help
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,200,000 (Direct Cost: ¥1,200,000)
This study was designed to explore the minimal light intensity needed to support maximum rate of lay in Japanese Quail (Coturnix Coturnix Japonica) under ahemeral (non-24-h) light-dark cycles.
Laying hens aged nineteen weeks were diving into three groups ; the first group were under middle light intensity, set at 70 lux, and the other two groups were under high light intensity, set at 1, 000 or 2, 000 lux. respectively. Total experimental duration was 144 days. Photo-periods during the first 42 days were 14L : 10D, next 42 days were 14L : 9D, and the last 60 days were 14L : 8D. The peak of oviposition time under 24-h cycle of middle light intensity (50 lux), was observed at 12-h after light-on, and the mean intervals between consecutive ovipositions were almost equivalent to the length of the cycle. The treatment of high (1, 000-2, 000 lux) intensity under 14L : 10D shortened the oviposition interval and concentrated the oviposition time in the period of the latter half of lighting. Und
er the high light intensity of 14L : 10D, free-running period (FRP) became prolonged. After changing the length of cycle to the 23h and 22h of the middle intensity lighting, however, oviposition rhythm was an intermediate between synchronized and free-running rhythms, and the rate of lay decreased compared with those of 24-h cycles. Rates of lay in middle intensity were 95% under 14L : 10D, and 86-88% under 14L : 9D and 14L : 8D. But, in 23-h cycle, the high light intensity had no effect on the rate of lay (24-h cycle ; 95-97%, 23-h cycle ; 94-96%, 22-h cycle ; 86-87%). It was obviously recognized that influence of the photoperiod on the egg production of coturnix differed by the light intensity.
From these results, we may concluded that high light intensity might increase the degree of entrainment of oviposition rhythm to photoperiod under 22-h and 23-h ahemeral light and dark cycle, and that the light intensity of about 1, 000 lux was probably the minimum which will support maximum rate of egg production in quail under 23-h light dark cycle. Because the Melatonin is probably peculiar to the pineal of mammals and birds. daily rhythms in the pineal content of melatonin and the biosynthetic activity supporting its synthesis are responsive to changes in environmental lighting, it is considered to be the main agent of pineal expression. The level of serum melatonin in the high light intensity was higher than that in the low and middle intensity lighting. Therefore, it may be that the light intensity play an important part in regulating the melatonin production mechanism in quail pineal gland. Less