Oct. IS, 1921 ' Influence of Plane Nutrition on Maintenance 



117 



CHANGES IN BODY WEIGHT 



In order to obtain data concerning the maintenance requirement of 

 these steers, it is necessary to calculate the energy gained or lost through 

 changes in body weight. Our calculations are based on analyses previ- 

 ously made by the Department of Agricultural Chemistry, University of 

 Missouri.^ Control animals were selected from those on which analyses 

 were available, on the basis of similar weights and measurements, and 

 when possible of similar ages, daily gains, and daily consumption of dry- 

 matter. In some cases suitable control animals were not available, and 

 the composition of steers for those periods was estimated by interpola- 

 tion, with the exception of the last period for steer No. 528. In this case 

 a value published by Armsby^ was used. The average energy values of 

 a pound gain as calculated by this method for steers in the three groups 

 are given in Table I. For purposes of comparison the values given by 

 Armsby are shown in the same table. 



Table I. — Energy values of a pound gain 



Approximate age (months). 



6. 

 18 

 36 

 54 

 66 

 78 



Group I. 



Therms. 



o- 95575 



1. 0918 

 I. 7136 



2. 1993 

 2. 50 

 3.00 



Group II. 



Therms. 



o- 95575 

 I- 0583 

 I. 1608 

 I. 4104 



I- 5352 

 I. 660 



Group III. 



Therms. 

 o- 8343 

 •9445 

 I. 0548 

 I. 1013 

 I. 4790 

 I. 6490 



Annsby's values. 



Age. 



Months. 



I 



2 to 3 



5 to 6 



II to 12 



18 to 24 



Energy. 



Therms. 



1. 170 

 1-374 



1.680 



2. 292 



3. 000 



Armsby's values are consistently higher, as is to be expected. Our 

 animals were thin and contained less than the usual amount of fat in the 

 gain. .; „.j'f u.-A ..■...■.:■' f.,^.. vjorf 



In calculating the maintenance requirements per 1,000 pounds live 

 weight, Moulton's ^ formula was used. He has shown that the surface 

 areas of thin cattle are proportional to the ^ power of the live weight. 

 The results of this calculation, on the basis of dry matter consumed, are 

 given in Table II. 



The net energy required for maintenance was also calculated by 

 another method,* based on the digestible organic matter of the feed. 



The following factors are given for the metabolizable energy of digesti- 

 ble organic matter consumed: Roughage, 1.588 therms per pound; grains 

 and similar feeds with less than 5 per cent digestible fat, 1.769 therms per 

 pound. In the same publication the "Average energy expenditure by 

 cattle per 100 pounds of dry matter eaten" is given. 



1 These have not yet been published. 



* Armsby, Henry Prentiss, op. cit. 



' MOULTON, C. R. THE AVAtLABILITY OF THE ENERGY OF FOOD FOR GROWTH. In Jour. Biol. Chem., V. 



31, no. 2, p. 390. 1917. 



* Armsby, H. P., and Fries, J. A. op. cit. 



