[The relationship between heart rate and type of growth in the domestic fowl]

The heart rate at 6 and 24 weeks of age and the relative weight of the heart at 8 and 24 weeks were studied in four strains of domestic fowl, differing in growth and, in this study, in body weight. Heart rate at 6 weeks of age was not related to sex, body weight, absolute or relative heart weight. Heart rate at 24 weeks of age was related to relative heart weight at 24 weeks, to absolute heart weight at 6 and 24 weeks, and to body weight at 6 weeks. There was a marked sex effect at 24 weeks. No within-species relationship between heart rate and body weight was found, but a negative correlation existed between heart rate and relative heart weight.