126 DAIRY CATTLE AND MILK PRODUCTION 



the cost of production. In any herd of 15 or 20 cows that has 

 not been carefully culled a greater total profit will be realized 

 by retaining from one half to two thirds of the herd and dis- 

 posing of the inferior ones. This is especially true of herds 

 composed of common grade and dual-purpose animals. 



One cow producing 300 pounds of fat in a year makes vastly 

 more net profit than do two producing 150 pounds each, 

 although the total production is the same in each case. The 

 reason can be easily understood when we consider the use 

 which the animal makes of its feed. The first use to which 

 the cow puts the feed given her, as is the case with any animal, 

 is to maintain body, which in this case is keeping the machinery 

 for milk production. The feed necessary for this purpose is 

 called the ration of maintenance. With an ordinary cow pro- 

 ducing 200 pounds of fat in a year, the ration of maintenance 

 represents from 50 to 60 per cent of the feed she consumes ; 

 in the case of a better producing cow about from 40 to 50 per 

 cent of her ration ; while an extraordinary producing cow may 

 not use over 35 per cent of her ration for this purpose. This 

 may be looked upon as a fixed charge which has to be made in 

 case of every animal, and since in any, except especially good 

 producing herds, at least half of the feed will be used for this 

 purpose it is clear that keeping two cows to do the work of one 

 is increasing the total amount of feed used by something like 

 25 per cent. 



Cause of the Variation in Individual Animals. An ex- 

 tensive investigation is reported by the Missouri Agricultural 

 Experiment Station on this point. 1 Two registered Jersey 

 cows were used; the better, known as No. 27, during the first 

 two lactation periods produced 3.9 pounds of fat and 2.8 



1 Research Bulletin No. 2. 



