BASAL KATABOLISM OF CATTLE AND OTHER SPECIES 



By Henry Prentiss Armsby, Director, J. August Fries, Assistant Director, and 

 WiNFRED WaiTE Braman, Associate, Institute of Animal Nutrition of The Pennsyl- 

 vania State College 



COOPERATIVE INVESTIGATIONS BETWEEN THE BUREAU OF ANIMAL INDUSTRY OF 

 THE UNITED STATES DEPARTMENT OF AGRICULTURE AND THE INSTITUTE OF 

 ANIMAL NUTRITION OF THE PENNSYLVANIA STATE COLLEGE 



INTRODUCTION 



The term "basal katabolism" has become generally accepted as a con- 

 venient designation for that portion of the katabolism due to the funda- 

 mental vital processes as distinguished, on the one hand, from that 

 arising from external muscular activities and, on the other hand, from 

 that caused by the ingestion of food. It is the katabolism of the animal 

 in a state of complete muscular rest and with the processes of digestion 

 and resorption suspended. It is the irreducible minimum of metabolic 

 activity consistent with a particular condition of the body. 



The basal katabolism in this strict sense is to some degree an ideal 

 conception, although a close approach to the ideal may be observed in the 

 postresorptive condition during short periods of complete muscular 

 relaxation. Basal katabolism as thus defined is, from a slightly dififerent 

 point of view, an expression of the minimum food requirement of the 

 organism. Any surplus above this minimum may either be utilized for 

 muscular activity or give rise to a storage of matter and energy. 



As regards the necessary food supply, however, a knowledge of the 

 basal katabolism in the strict sense is of limited utility. A state of 

 complete muscular inactivity can not be maintained for any considerable 

 time, while even slight exertion augments the katabolism to a marked 

 degree. In estimating the food requirements for the performance of a 

 given amount of work by man or domestic animals, or for the storage of a 

 specific quantity of protein and fat in the form of meat or milk, the base 

 line is afforded, not by the katabolism during short periods of absolute 

 rest but by the fasting katabolism of the individual under average con- 

 ditions of living. Particularly is this true of the feeding of domestic 

 animals for the production of human food. The dairy cow or the fattening 

 steer must receive enough feed to supply its incidental daily activities as 

 well as its minimum katabolism in a state of absolute rest before any is 

 permanently available for manufacture into milk or meat. This amount, 

 commonly spoken of as the maintenance requirement, is measured by 

 the fasting katabolism under average conditions and may be called the 

 24-hour basal katabolism. Obviously, this is not as sharply defined a 

 conception as is the basal katabolism in the narrower sense, but its 

 practical importance is evident. 



Journal of Agricultural Research. Vol. XIII. No. i 



Washington. D. C. Apr. i. 1918 



mp Key No. Pa.— 6 



(43) 



