The California apparatus for respiration trials with large animals

Abstract

does not appear. First page follows. Energy metabolism is one of the fundamental vital functions. Its measurement is therefore the key to a great many physiological problems. In the field of animal nutrition, the determination of the energy exchange enables the investigator to express the effect of food in terms of gain or loss of chemical energy instead of using the less reliable criterion, body weight. The main objects of investigation in this field are determination of relative food values; measurement of the effect of environmental conditions, methods of feeding, and quality of food on food utilization; and determination of the relative values of animals as utilizers of food, with a view to securing data which may become important for genetic purposes. This paper discusses the problems involved in the measurement of energy metabolism in large animals and describes the respiration apparatus in operation at the Branch of the College of Agriculture, University of California, Davis, California. The apparatus was constructed in 1929 and 1930, and more than three hundred measurements of the 24-hour metabolism of cows and heifers have been conducted up to this time. The apparatus may therefore be regarded as completed for its present purpose. It will, however, be further developed as experience with its operation grows and as new problems calling for its use may demand. In order to simplify future reports on results obtained with this apparatus, it seems desirable to describe it in its present state, together with the procedure followed in respiration trials with cattle at this experiment station.