SELECTION OF THE INDIVIDUAL COW 129 



food for producing milk was limited to about one third that of 

 No. 27. That is to say, No. 27 was a more efficient milk-pro- 

 ducing machine on account of a greater capacity to use food 

 above maintenance. The food she consumed was not used to 

 any better advantage than that eaten by the inferior cow. 



No. 62 required 55.8 per cent of her ration for maintenance, 

 and No. 27 only 35 per cent. 



The problem may be illustrated graphically by the lines 

 below : 



No. 27 

 Ration of maintenance Used for milk production 



I 1 1 



35 per cent of ration 65 per cent of ration 



From the standpoint of economical production No. 27 is a 

 very profitable cow, while No. 62 does not pay for her feed. 

 In the course of the above investigations the data were com- 

 pared from two other Jersey cows, and the statements given 

 found to apply to all. 



By the foregoing statement it is not meant that the su- 

 perior cow had a greater digestive capacity necessarily than 

 the inferior. The experiment above described explains how 

 the two animals used the feed given them, but it does not in- 

 dicate the real reason why the one animal secreted three times 



