25 



grains and the various by-products and mix his own rations than 

 to purchase proprietary mixtures. Exceptions to this rule may 

 occur. 



If he buys feeds chiefly for their protein, those richest in that 

 ingredient are usually the cheapest. If he purchases feeds prima- 

 rily for their content of digestible matter, the cereal grains are, 

 as a rule, the more economical. Between these two groups there 

 are many feeds that have a fair amount of protein and are quite 

 high in digestibility. 



Relative Values of Feeds. The best way known for measuring 

 the relative values of cattle feeds is the net heat or energy 

 method. The entire amount of heat or energy contained in a 

 feed is termed its total heat or energy value. All of this energy 

 cannot be used by the animal, portions being lost in the form of 

 faeces, urine, in the heat radiation as a result of work required in 

 chewing, digestion and assimilation and thru the influence of cer- 

 tain feeds in stimulating the metabolism. These several losses, ex- 

 pressed as energy (calories), deducted from the total energy, leaves 

 the net heat or available energy values. 



Here follows a list of feedstuffs showing their percentages of 

 digestible protein and their relative values, corn meal being used 

 as 100 for convenience of comparison:* 



(a) Cereals 



Digestible Relative 



Protein Net Energy 



(Per Cent) Values 



Corn Meal 6.9 100 



Barley 9.0 105 



Buckwheat 8.1 70 



Corn-and-Cob Meal 6.1 89 



Oats 9.7 79 



Rye '. 9.9 110 



Wheat 9.2 107 



(b) Oil Seed Residues 



CocoanutMeal 18.8 98 



Cottonseed Meal 33.4 105 



Germ Oil Meal (from corn) 16.5 98 



Linseed Meal (new process) 31.7 100 



Linseed Meal (old process) 30 . 2 104 



* Adapted from Bui. 142, Pena. Experiment Station, by H. P. Armsby. 



