JOM£ OF AGRICETIAL RESEARCH 



DEPARTMENT OF AGRICUETURE 



Vol. Ill Washington, D. C, March 25, 191 5 No. 6 



NET ENERGY VALUES OF FEEDING STUFFS 

 FOR CATTLE 



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

 histitute of Animal Nutrition of The Pennsylvania 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 



Besides supplying certain specific forms of matter (ash ingredients, 

 proteins, lipoids, carbohydrates, vitamines, etc.) essential to the normal 

 course of metabolism, the feed of an animal is, so far as we know, the 

 sole source of the energy whose transformations constitute the essential 

 phenomena of physical life. This energy is contained in the feed as 

 chemical energy, and the maximum quantity which any substance can 

 furnish for the vital activities by its oxidation in the body is measured 

 by its heat of combustion. It rarely, if ever, happens, however, that 

 this maximum effect is realized. In practically every case a larger or 

 smaller proportion of the chemical energy of the feed escapes unutilized. 

 These losses of energy are of two general classes. 



First, a portion of the chemical energy of the feed fails to be trans- 

 formed at all, leaving the body as chemical energy in the visible excreta 

 and in the combustible gases arising from gastric and intestinal 

 fermentations. 



Second, another portion of the chemical energy of the feed is indeed 

 transformed, but at ordinary temperatures virtually results merely in a 

 superfluous heat production. It is true that the metabolism consequent 

 upon feed consumption is not only unavoidable but may be regarded as 

 a necessary expenditure of energy for the support of the activities con- 

 nected with digestion and assimilation. Nevertheless, from the stand- 

 point of the net gain or loss by the organism this portion of the feed 

 energy, which ultimately takes the form of heat and escapes from the 

 body, must be regarded as a loss. 



The remainder of the chemical energy in the feed, after deducting these 

 two classes of losses, has been designated as its net energy value and 



Journal of Agricultural Research. Vol. Ill, No. 6 



Dept. of Agriculture, Washington, D. C. Mar. 35, 1915 



A-13 

 (43 s) 





