FORTY-SECOND ANNUAL CONVENTION 241 



energy and heat-producing constituents by the fat and sugar. 

 In addition to the constituents or compounds necessary for the 

 production of milk, she also must have the constituents neces- 

 sary for performing the other functions mentioned. These, for 

 convenience, have been classified into proteins, carbohydrates, 

 and fats. Fats perform much the same functions as carbohyd- 

 rates and are worth for production practically two and one- 

 fourth times as much per pound as carbohydrates, and in the 

 balancing of a ration are usually classed with them. This brings 

 us to a definition of a ''balanced ration," which is a ration con- 

 taining these various nutrients in the proportion the cow needs 

 them. 



The economical importance of a balanced ration is evident. 

 The cow can use only certain elements or compounds in certain 

 proportions; consequently, if the ration supplies an excessive 

 amount of any one, the excess is liable to be wasted. Not only 

 is this true, but as the cow has to assimilate it even though she 

 can not use it, her capacity for production is reduced. 



Cost. 



In making a ration, cost is one of the important factors. 

 The best practice is to compound a grain mixture so that it will 

 balance with the home-grown roughage. With this in mind, the 

 separate grains should be selected to supply the necessary nutri- 

 ents at the lowest possible cost. For this, not only the price per 

 hundred pounds but also the relative cost of each constituent; 

 especially protein, must be considered. For example, to determine 

 the cost of a pound of digestible protein in a given feed di- 

 vide the price of lOO pounds by the per cent of digestible protein 

 in the feed. If this calculation is made for several feeds, the 

 relative cost of protein in each will be apparent. Then the feeds 

 that furnish protein at the least cost can be selected. The same 

 can be done to determine the cost of the carbohydrates and fat. 

 which are the heat-making or energy-producing part of the feed, 



