44 DOMESTICATED ANIMALS AND PLANTS 



commercial herds of the state, this difference is exceedingly sig- 

 nificant. Rose was, of course, an exceptional cow, producing in 

 another test over two and one-half times as much as her com- 

 petitor, and making a twelve-year record of 7258 pounds of 

 milk, and 360 pounds of butter fat on the average (384 pounds 

 of fat for ten years), and never being beaten but once in all the 

 dairy tests ever conducted at this station. Professor Mumford, 

 also of the University of Illinois, has shown that substantially 

 the same differences exist between beef animals in respect to 

 the amount of gain for food consumed, 1 so that the principle 

 involved seems general. 



Economic significance of differences in efficiency. The mean- 

 ing of all this is not at once clear, and some little effort is 

 needed to fully appreciate the economic significance of differ- 

 ences such as are here brought out, and the consequent desira- 

 bility of bringing our common animals to the highest possible 

 degree of efficiency. When one cow can make two and one- 

 half times as much as another on the same feed, the difference 

 is not as two and one-half is to one, but many times greater. 

 Under these conditions, when one cow makes 100 pounds of 

 butter, the other will make 250 pounds on the same feed ; but 

 the question of relative profits depends also upon two other 

 factors, — the cost of feed and the price of butter. For the sake 

 of illustration let us suppose, first, that it costs the value of 

 50 pounds of butter to pay for the food consumed, which is the 

 same in both cases. The profit would then be, in the one case, 

 the value of 100—50 (or 50) pounds of butter; and in the 

 other, 250 — 50 (or 200) pounds, which is not two and one-half 

 bid four times as much. 



Suppose again that feed is higher or butter lower, so that it 

 now costs the value not of 50 pounds but of 90 pounds to pay 

 for the cost of feed. In this case the profit for the poorest cow 

 is the value of 100 — 90 (or 10) pounds of butter, and for the 

 other it is the value of 250 — 90 (or 160) pounds of butter, 



1 See " Principles of Breeding," p. 82. 



