472 NUTRITION OF FARM ANIMALS 



Even the lowest of these records are remarkably good considering 

 the unfavorable conditions necessarily incident to a public test. In 

 each of these three picked herds, however, the production of the 

 poorest animal was only from 50 to 60 per cent of that of the best 

 animal. Moreover, the differences between individuals of the same 

 breed were much greater than the differences between the averages 

 for the three breeds. That even greater differences exist among the 

 common cows of the country has been shown by numerous statistical 

 investigations, some of the most striking of which have been col- 

 lected by Eckles. 1 



562. Influence on economy of feeding. While it is un- 

 likely that the utilization of the feed in the narrower sense 

 (i.e., the amount of milk solids of a given composition manu- 

 factured in the udder from equal amounts of nutritive substances 

 supplied) is materially affected by the individuality of the 

 animal, the feed utilization in the broader economic sense is 

 very largely dependent upon this factor. It must be con- 

 stantly borne in mind that, as already stated (558), efficiency 

 in milk production is in large part a question of the distribution 

 of the feed supplied in excess of maintenance. Some animals, 

 by virtue of individual or inherited peculiarities, are able to 

 transform large amounts of excess feed into milk without stor- 

 ing up any considerable portion of it in the form of body tissue. 

 Such animals tend to remain spare in body and if well fed 

 produce large amounts of milk. They are the typical dairy 

 animals. Other individuals, on the contrary, have a well- 

 marked tendency in the opposite direction, viz., toward the 

 production of body tissue. When fed heavily, they utilize 

 the additional feed chiefly in this direction and show little or 

 no tendency toward an increase in milk production. These 

 are typical meat-producing animals. The two types, of course, 

 shade into each other by imperceptible gradations. 



The important bearing of these facts upon the nutrition of 

 dairy animals will be further considered later (606-610). 

 Here it may simply be noted that the superiority of cer- 

 tain individuals which has been illustrated in the preceding 

 paragraphs is doubtless due to a considerable extent to the 

 ability to consume large amounts of feed and convert the sur- 

 plus into milk rather than into body tissue. 



1 Dairy Cattle and Milk Production, IQII, pp. 118-126. 



