生長期におけるウズラの精巣発育と光周期

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Experiments were performed to investigate the effect of the length of photoperiods on testicular maturation and body weight gain of Jpanese quails (Coturnix coturnix japonica) during their early life (Exp. I, 1-8 and Exp. I, 9-12). The modification of testicular growth under 8-hour daily photoperiods by the insertion of a light period of 32 hours or more was also investigated (Exp. II and Exp. III). Birds were reared at a temperature of 26°±1℃ and illuminated by day-light fluorescent tubes which gave a light intensity of 500-1,000 lux on the floor of aviaries. In Experiments I, 1-8 and II, 250 birds were kept under constant light (24L) during the first two weeks of life. Ten birds among them were sacrificed at the end of this period to examine their testes, and the remainders were divided into two groups: one group subjected to 8-hour daily photoperiods (8L) and the other to 16-hour daily photoperiods (16L). In Experiments I, 9-12 and III, quails of 25 days of age, which had been reared under long daily photoperiods untill this time, were divided into two groups and kept under 8L and 24L, respectively. Most birds subjected to 16L produced spermatozoa within the first 40 days of life, and the testes of all birds reached maximum weight at 55 days of age. The retardation of maturation occurred in the 8L-birds as compared with 16L-birds; the growth of testes started at about 70 days of age, and only half of the birds showed full maturation even at an age of 128 days. In Exp. I, 8, each quail of 8L and 16L was transferred to separate cages at 34 days after hatching, and the increase of he body weight was traced thereafter. The avarage gain in weight of 8L-birds was not significantly different from that of 16L-birds untill 44 days after hatching. Although the body weight of 8L-birds kept on increasing afterwards, that of 16L-birds remained almost constant until 58 days of age and thereafter increased rapidly. On the 106th day of age, no significant differences were found between the body weight of 8L-birds and that of 16L-birds. The results suggested the existence of some relationships between the increase in body weight and the maturation of the testes. In Exp. II and III, a light period of 32 hours or more was inserted into the cycle of 8 hour light-16 hour darkness. 8L-birds of Exp. IIa and IIb received 56- and 32-hour light periods respectively at 55 days of age, and the testes were examined at 12 days after the end of the inserted light period. In Exp. III, 8L-birds of 53 days of age were treated with two light periods: a 8-hour dark period wa put between a 20-hour light period and a 48-hour light period. Such treatment of birds with the photoperiod insertion was found to evoke testicular growth, while the testes of untreated birds scarcely grew under 8L-conditions (8L-birds, Exp. I, 4-5 and Exp. I, 11-12). The degree of testicular growth tended to increase with the length of the inserted light period. These results indicate that a rhythm composed of light and dark periods may play an important role in the testicular development of Japanese quails.
社団法人日本動物学会の論文
1965-02-15

生長期におけるウズラの精巣発育と光周期

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