The effect of milk given at various temperatures on the oxygen consumption of young calves

SUMMARY1. Measurements of oxygen consumption and rectal temperature were made on young female calves at air temperatures of 9° and 20°C, before and after 4·5 kg milk was drunk at 23° and 39°C.2. When cool milk (23°C) was drunk at an air temperature of 9°C, vigorous shivering occurred, and during the 2-hr period after feeding, oxygen consumption was significantly higher than in the three other treatments.3. In all other treatments oxygen consumption increased considerably during the 30-min period which included drinking activity; the average increment, when no thermo-regulatory shivering occurred, was 1·9 ml O2 min−1kg−1.4. It was estimated that the 58 kcal ‘heat of warming’ required by milk at 23°C drunk at an air temperature of 9°C could be accounted for by the increment in heat production during the 2 hr after feeding and the fall in rectal temperature of 0-2-0-3°C which persisted after feeding in this treatment. These calculations suggested that the effect of a cool liquid on the energy balance of an animal would be less than that predicted from the ‘heat of warming’ required by the cool liquid.