Mar. 2s. 191S Energy Values of Feeding Stuffs for Cattle 487 



of the methane estimated from the amount of carbohydrates digested. 

 When this is not practicable, it was further shown that the metabolizable 

 energy may be estimated from the total digestible organic matter by the 

 use of the factors given on pages 451-453. In one or other of these ways 

 it is not difficult to compute approximately the metabolizable energy of 

 the more common feeding stuffs, while the subtraction from this of the 

 average energy expenditure due to feed consumption will give the net 

 energy value. To illustrate, E. W. Allen, ^ gives the following data for 

 average alfalfa hay, oat straw, and wheat bran: 



Percentage of dry matter and digestible food ingredients of feeding stuffs 



.\lfalfa Oat Wheat 



hay. straw. bran. 



Total dry matter 91.6 90. 8 88. 5 



Digestible: 



Protein 10.58 1.20 12.01 



Carbohydrates 37-33 38-64 41-23 



Fats 1.38 0.76 2.87 



Total digestible 49- 29 40. 60 56. 11 



The sum of the digestible protein, carbohydrates, and fat equals, of 

 course, the total digestible organic matter, irrespective of its chemical 

 composition. Each gram of digestible organic matter, according to the 

 averages on pages 451-453, would contain 3.5 Calories of metabolizable 

 energy in the coarse fodders and 3.9 Calories in the bran. The average 

 losses of energy in heat production per kilogram of feed would be the 

 amounts shown on page 482 reduced to the average water content of 

 the feed, as follows: 



Alfalfa hay . . 1,169X0.916=1,071 Calories. 



Oat straw 1,014X0.908= 921 Calories. 



Wheat bran . 1,138X0.885=1,007 Calories. 



The computation of the net energy values is therefore as follows: 



Alfalfa hay (3.5 Calories X492. 9) — 1,071 Calories=654 Calories per kilogram=29.7 T. 



per 100 pounds. 

 Oat straw (3.5 CaloriesX4o6.o)— 921 Calories=5oo Calories per kJlogram=22.7 T. 



per 100 pounds. 

 UTieat bran (3.9 CaloriesXs6i.i) — 1,007 Calories=i,i8i Calories per kilogram=53.6T. 



per 100 pounds. 



The methods of comptitation just illustrated are perhaps open to the 

 charge of being to a degree summary and empirical. The idea of basing 

 such computations on the energy values of the single ingredients may 

 be fundamentally more scientific, but unfortunately at present it is 

 an impracticable ideal on account of our deficient knowledge of the 

 chemistry of feeding stuffs and of the physiological values of their in- 

 gredients. While investigation along both these lines is highly inii)ortant 

 and desirable, yet for a long time to come the data on which to base the 

 practice of stock feeding will have to be obtained by more direct even 



' Allen, E. W.. The feeding of farm animals. U. S. Dept. Agr. Farmers' Bui. as (rev.), p. 8-9. 1901. 



