Effect of Photoperiod on Cyclic Patterns of Body Temperature in the Quail

Abstract

THE nature of body temperature rhythms in gallinaceous birds can best be described when exogenous factors such as disturbances, movement (muscular activity), and temperature extremes are controlled. Normal fluctuations in body temperature usually are associated with concomitant forms of daily activity. The magnitude of variation differs considerably among species. In chickens kept in an uncontrolled, but moderate, environment the diurnal differential in body temperature is approximately 1.3° C (refs. 1 and 2). The highest body temperature occurs at 1700 h and the lowest at 0400 h. In a controlled environment where temperatures were held constant at 21.1° C, the diurnal body temperature change in chicken was 0.17° C (ref. 3). The body temperature of Gambel quail (Lophortyn gambelii) maintained at ambient temperatures between 24° and 26° C fluctuates between 40° and 41.5° C during the day and has a range approximately 1.5° C lower during the night⁴. Most investigators agree that activity per se is the principal factor which causes change in body temperature. Since the light period induces or exaggerates activity, it is of interest to determine the influence different photoperiods have on altering the circadian changes of body temperature in coturnix (Coturnix coturnix japonica).