Productive Value of Typical Nutrients 177 



of a fattening animal also modify the efficiency of the 

 food for production purposes, as does the period of lac- 

 tation with a cow. With all these variations we have 

 no averages which express with any definiteness the 

 relative ' practical production value of the different nu- 

 trients. Nevertheless this question has been the sub- 

 ject of severe and extended investigation, and some of 

 the results have given valuable information. 



Henneberg and Pfeiffer estimate that in experiments 

 with sheep the protein in excess of maintenance caused 

 the production of from 30.7 to 41.1 parts of fat for 

 each 100 parts of protein. It is not shown that the 

 fat came directly from the protein or from the carbo- 

 hydrates which the excess of protein replaced in other 

 uses. Experiments by Kiihn are made the basis of 

 the conclusion that 1 pound of starch supported the 

 storage of .2 pounds or fat. 



The most reliable and extensive data as to pro- 

 ductive values are those already referred to as having 

 been reached by Kellner and others at Mockern. They 

 are summarized in the following table: 



Heat Mainten- Percentage Productive Corapara- 



value ance value Mainten- value tive 



gram gram ance value gram productive 



organic organic applied to organic value 



matter matter production matter starch 100 



cal. cal. Per cent cal. 



Starch 4183 3760 58.9 2215 100 



Extracted straw... 4247 3651 63.1 2304 104 



Molasses 4075 3645 63.6 2310 104 



Meadow hay 4480 3640 41.5 1512 68 



Oat straw 4513 3747 37.6 1409 64 



Wheat straw 4470 3327 17.8 592 27 



Gluten 6148 4958 45.2 2241 101 



Peanut oil.. 8821 8821 56.3 4966 224 



