144 DAIRY CHEMISTRY 



a tendency to encourage a larger flow of milk dur- 

 ing later periods of lactation. 



In the feeding of dairy stock, sudden changes in 

 the ration should be avoided. In case it is necessary 

 to make a change in the coarse fodder or grains, it 

 should be done gradually. A good feeder can tell 

 from the appearance of the stock and the avidity 

 with which the ration is consumed whether the 

 grains and coarse fodders are being fed to advan- 

 tage. In many of the feeding trials that have been 

 made, the experimental periods have been too short 

 to give reliable results. 



136. Comparative Cost and Value of Grains. The 

 market and feeding value of grains often vary between 

 wide extremes, and it is frequently found that a given 

 sum of money, if invested in one food, will procure a 

 larger amount of digestible nutrients than if invested 

 in other foods. In general, it can be said that there 

 is but little difference in the milk-producing value 

 of grains when fed in a mixed ration, and hence the 

 price per pound can be taken as the deciding factor 

 as to what shall constitute the main part of the ration. 

 In case it is desired to compare the amount of nutri- 

 ents that can be procured for a given sum of money, 

 it can be done in the following way : Determine the 

 number of pounds of food material that can be pur- 

 chased for $ 1.00, and then calculate the number of 

 pounds of digestible nutrients in this quantity of food. 

 For example, if oats are 30 cents per bushel, a dollar 

 will purchase 107 pounds. Since 100 pounds of 



