PRINCIPLES OF AGRICULTURAL CHEMISTRY 



acid for the purpose of forming bones. A deficiency of either 

 of these is liable to cause injury, or disease. In certain localities, 

 the food is deficient in ash. Deficiency in lime alone is corrected 

 by the use of precipitated chalk; in phosphoric acid, by the use 

 of precipitated or ground phosphate of lime. 



Exact Calculation of a Ration. Before beginning to calculate 

 a ration, it is necessary to decide on the ration desired, the feeds 

 available, and their probable composition. In calculating the 

 ration we must consider: 



(1) The desired productive value. 



(2) The desired bulk. 



(3) The desired proteid content. 



All these may vary somewhat, especially the bulk and the 

 proteids. 



We will term the method of calculation given below, the method 

 of substitution. It is best illustrated by an example. Suppose 

 we desire a ration with a bulk of about 28 pounds, proteids 2.0 

 pounds, and productive value of 2.8 pounds, and wish to use 

 corn chops, cottonseed meal, and cottonseed hulls, having the 

 composition given in the table at the end of this chapter. As 

 these feeds all contain about ten per cent, water, for which allow- 

 ance has been made in considering the total bulk to be fed, it is 

 not necessary to calculate to dry matter. 



First, let us assume that the 28 pounds fed is entirely cotton- 

 seed hulls. This quantity of cottonseed hulls has a productive 

 value of 0.84 pounds, and the value desired is 2.80 pounds, leaving 

 a deficiency of 1.96 pounds. If now we replace cottonseed hulls 

 having a productive value of 0.03 a pound by corn chops, having a 

 productive value of 0.206, for every pound of cottonseed hulls re- 

 placed, we gain 0.206-0.03 - 0.176 pounds productive value. 

 Dividing 1.96 by 0.176 we have n.i pounds corn chops, which 

 should replace an equal amount of cottonseed hulls. 



Cottonseed hulls 17.9 pounds and corn chops n.i pounds con- 

 tain 0.86 pounds proteids, while 2.0 pounds is desired, a de- 

 ficiency of 1.14 pounds proteids. Since cottonseed meal has 



