294 AGRICULTURAL ECONOMICS 



90. VARYING PRODUCTIVITY OF INDIVIDUAL UNITS IN THE 



SAME CLASS OF CAPITAL-GOODS 1 



BY E. DAVENPORT 



Again, no two individuals of the same species can be depended 

 upon to give exactly the same quality of milk, for herd records show 

 that the milk of different cows varies naturally from less than 3 per 

 cent to more than 6 per cent fat. Nor is this dependent upon the 

 food supply, for all authorities agree that the proportion of fat to 

 other solids is dependent upon the individual and not upon her 

 feed. Moreover, differences nearly as wide as these quoted may be 

 found within the limits of a single herd and therefore under identi- 

 cal conditions as to feed. Still again, two individuals of the same 

 breed will produce radically different amounts of milk or fat, 

 whichever is measured, from identical amounts of the same kind 

 of feed. 



Three experiments were conducted to determine the limits of this 

 difference between cows considered good enough for a place in a com- 

 mercial herd. In the first, Eva produced 48 per cent more milk and 

 1 1 per cent more butter in ninety-one days than did Janet, and in so 

 doing consumed no more garin and but 7 . 6 per cent more roughness. 

 These cows were both mature, were fresh on the same day, and 

 neither suffered accidents during the experiment, yet Eva produced 

 1,057 pounds of milk and 12 pounds of butter fat out of her extra 

 feed of 112 pounds of hay and corn stover. The second experiment 

 was a comparison between Rose, a native cow nine years old, and 

 Nora, a native cow six years old. Rose commenced April 13 and 

 Nora May 22, 1899, and both were milked for a full twelve months. 

 Both were in good health, and both continued in good flow until the 

 last, Rose averaging over 18 pounds of milk per day and Nora nearly 

 14 pounds for the last seven days of the test. Each consumed all the 

 feed she cared to take, the only restriction being that its composition 

 was the same for both. Neither was in any sense beefy, but Rose 

 gained 181 pounds and Nora 165 pounds from August i to April i, 

 showing that they were evidently working at or near their limit of 

 milk production. 



Rose consumed slightly the heavier ration and yielded decidedly 

 the larger product in both milk and fat. The accompanying table 



1 Adapted from Principles of Breeding, pp. 78-81. (Copyright by Eugene 

 Davenport. Published by Ginn & Co.) 



