Heart Rate of Chickens Determined by Radio Telemetry during Light and Dark Periods

Diurnal variation in activity, body temperature, and metabolic rate in chickens and other birds has been studied and reported by a number of investigators (Sturkie, 1954; King and Farner, 1961). Since heart rate is known to be influenced by these parameters, it might be expected to exhibit diurnal variation. No really critical experiments have been conducted on the heart rate of unrestrained birds under normal conditions. Most data on heart rate were obtained on birds restrained and subject to excitement and handling, and the rates are quite variable (Sturkie, 1954; McNally, 1941). Some have considered a resting or basal heart rate as one obtained on a bird that was restrained and kept quiet for varying periods of time. In recent years radio telemetry has been employed to determine heart rate in humans, cats, dogs, and rabbits (Essler and Folk, 1961) under normal conditions, free of restraint and excitement. In general,…