Types of Oviposition Rhythm Classified by Length of Oviposition Intervals and Characteristics of each Type in the Quail (Coturnix coturnix japonica)

Experiments were designed to classify types of oviposition rhythm in the quail by an average interval of successive ovipositions observed in individual hens and to find out characteristics of the respective oviposition types. Hours of ovipositions in 72 hens under 14L: 10D were recorded throughout the period of 26 days. Depending on the length of an average oviposition interval, three groups, each composed of ten individuals, were selected from 56 hens showing over 80% egg production during the experimental period; one group showing a longer interval between ovipositions was designated A type (non-entrained pattern), the second group which showed a shorter interval was designated C type (entrained pattern) and the third group which showed an intermediate interval was designated AC type (intermediate pattern). The mean oviposition interval of A, C and AC types was 26.5, 24.0 and 24.9 hours, respectively. Hens belonging to A and AC types showed a tendency to restrict their ovipositions during the period from the latter half of the lighting period to the earlier half of the dark, although some ovipositions were observed during the other part of the day. A peak of oviposition was observed 13-14 hours after light-on in hens of A and AC types. The distribution pattern of frequency of oviposition intervals classified every 0.25 hours in A type revealed the lowest concentration among the three types. In this type, the difference between the longest and the shortest interval was 9 hours and the median value was 27.5 hours. In C type, 88% of their eggs were laid at intervals of 23-25 hours. These findings indicate that the hens showing different oviposition rhythms reveal a different mean oviposition time and a different distribution pattern of the frequency of oviposition intervals. In the hens of A type, the interval of oviposition was always longer than those of other types at any hours. The results suggest that an endogenous clonomechanism may play a part in the manifestation of oviposition types in the quail.