THE RATIONAL FEEDING OF DAIRY STOCK 137 



amount of heat is directly proportional to the per- 

 centage of fat, carbohydrates, and proteids present. 

 A balanced ration produces about 32,000 calories, or 

 heat units. A calory is the unit of heat, or the 

 amount of heat required to raise 1 kg. of water 1° 

 on the centigrade scale, or one pound of water about 

 4° on the Fahrenheit scale. A pound of digestible 

 fat produces 4225 calories, and a pound of digest- 

 ible carboliydrates or protein produces 1860 calories. 



133. Nutritive Ratio. — The term "nutritive ratio" 

 is used to express the ratio which exists between the 

 digestible jjrotein and the digestible carboh3'drates. 

 A nutritive ratio of 1 to 6.5 means that there is one 

 part of digestible protein to 6.5 jjarts of digestible, 

 non-nitrogenous compounds. A wide ration means 

 a large proportional amount of carbohydrates to 

 protein, while a narrow ration means a compara- 

 tively small amount of digestible carljohydrates to 

 protein. In calculating the nutritive ratio, the crude 

 fat or ether extract is multiplied by 2.25, because 

 the fats are 2.25 times more concentrated than the 

 carbohydrates. 



134. Selection of Foods for Rations. — In the feed- 

 ing of dairy animals the selection of the food mate- 

 rials is of equal importance with the amount of 

 nutrients they contain, because, as stated in a pre- 

 ceding chapter, the amount and quality of the milk 

 and products are dependent largely upon the charac- 

 ter of the foods consumed. To give the best results, 

 a ration should contain grains, mill products, coarse 



