Study of circadian rhythmicity of physiological response and skin temperature of sheep during summer and winter in semi-arid tropical environment

The present study aimed to evaluate the circadian rhythmicity of some physiological variables, including rectal temperature (RT), respiration rate (RR), heart rate (HR) and skin temperature (ST) in sheep during the summer and winter in semi-arid tropical environment. Eight Malpura rams of 3-4 year of age with an average body weight of 37.1 ± 1.99 kg were selected for the study. All the animals were fed individually for a maintenance requirement on a body weight basis. The RT, RR, HR and ST values were measured in each animal at 3 hour intervals for 24 consecutive hours. Ambient temperature (DBT) and relative humidity (RH) was also recorded inside the shed at the time of physiological parameter study. The cosinor analysis showed a daily circadian rhythm (P < 0.01) in RR, HR and ST values during the summer and winter in sheep under semi-arid environment. The RR, HR and ST differ significantly (P < 0.05) between summer and winter. The amplitude of RR, RT and ST differ significantly (P < 0.05) between the seasons. The results indicate that the circadian rhythmicity of RR, HR, RT and ST during summer and winter changed as expected in compliance to the seasonal requirements of animal's adaptability.