Daily rhythms of colonic temperature and circulating blood enzymes,urea and calcium in Japanese quail (Coturnix coturnix japonica) under natural cold-dry (harmattan) and hot-dry conditions

The influence of cold-dry (harmattan) and hot-dry seasons on daily rhythmicity of colonic temperature (CT) and blood biochemical variables were investigated in 340 male Japanese quails under natural light–dark circle. Rhythm characteristics analysed using cosinor and the application of the periodic model showed a daily rhythm of CT, creatinine phosphate kinase (CPK), aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase (ALP) and urea in both seasons, while calcium did not exhibit any rhythmicity. The rhythmic parameters of mesor, amplitude and acrophase analysis showed significant (p < 0.05) effects of season. The amplitudes, except for ALP, were greater during the harmattan. The acrophase, except for CPK and urea, were all restricted to the light phase of the light-dark cycle. The results, demonstrated strong seasonal changes on the daily rhythmicity of CT and blood biochemical parameters of quails under natural light-dark circle, which could be useful for researchers, clinicians and agriculturists under different climatic conditions.