62 FORAGE PLANTS AND THEIR CULTURE 



values of the digestible proteins, carbohydrates and fat 

 a pound in timothy taken at $15 a ton, bran at $27.60 

 a ton, gluten feed at $30 a ton, cottonseed meal 

 at $32 a ton, and alfalfa at $20 a ton. By comparing 

 timothy with each of the others in order the value of 

 the carbohydrates is determined respectively as $.012, 

 $.015, $.014 and $.014 a pound, an average of $.014. 

 The respective values for the protein are $.066, $.025, $.025 

 and $.041 a pound, an average of $.039. The average 

 value of the fat similarly determined is $.032 a pound. 



In the other four columns of the table arbitrary values 

 are given to the nutrients for comparison. 



In a general way the figures show correspondence to 

 market value. How nearly they may represent the true 

 relative values of the feeds does not appear in the light of 

 present knowledge. 



53. Net energy values. The energy value of a feed is 

 determined by an instrument called a calorimeter, and 

 is measured in therms of 1000 calories. A calorie is the 

 amount of heat required to raise 1 kilogram of water 1 

 degree Centigrade. 



The net energy value of a feed is that which remains 

 after deducting from its total energy value that lost in the 

 feces, in the urine, in gases and in the work of mastication, 

 digestion and assimilation. The loss in gases and in the 

 labor of assimilating the feed is measured by keeping the 

 animal in a special apparatus the respiration calorim- 

 eter. 



From investigations conducted at the Pennsylvania 

 Experiment Station, Dr. H. P. Armsby has determined 

 the net energy values for a number of roughages as well 

 as concentrates. The energy values of the roughage 

 feeds are shown in the following table : 



