The estimation of energy expenditure from heart rate measurements in working oxen and buffalo

Abstract

SummaryThe heart rates and corresponding energy expenditure of adult Brahman cattle (Bos indicus) and water buffalo (Bubalus bubalis) were measured whilst they were standing, walking at speeds of up to 1 m/sec and pulling loads of up to 50 kg for periods of 1–2 h/day. Correlations of heart rate with energy expenditure showed a positive linear relationship within species although a distinct difference was exhibited between species. However, when heart rate and energy expenditure were expressed relative to their respective resting values (RHR and REE respectively), the results for all animals fitted the same line:REE = 2·251 RHR – 0·954 (r = 0·93; n = 49).More importantly, the relative heart rate and actual energy expenditure per unit metabolic body weight (EEW) for all animals fitted a common line:EEW = 24·94 RHR – 16·25 (r = 0·91; n = 49),where EEW is in watts/kg0·75 and RHR = heart rate of the working animal/heart rate at rest. This assessment of the energy expenditure from measurement of heart rate and live weight thus allows a prediction to be made of the energy requirements of working draught cattle under field conditions.