78 FEEDS AND FEEDING 



higher in net energy than that eaten by older animals. In addition, 

 since young animals consume much more feed in proportion to live 

 weight, they have left for building into body tissues a much larger 

 part of their feed after the maintenance requirements of the body have 

 been met. These factors account fully for the greater economic effi- 

 ciency of younger animals. Contrary to common popular opinion, there 

 is no evidence that a young animal makes any better percentage utiliza- 

 tion of the net energy supplied in the feed than an older one. 7 



From the practical standpoint, it is of prime importance in feeding 

 animals for meat production to take advantage of the great stimulus to 

 growth when animals are young. Growing animals should therefore 

 always be fed rations rich enough in protein and mineral matter to per- 

 mit rapid and economical growth of body tissues and skeleton. 



115. Milk the natural food for young mammals. Since milk is Nature's 

 food for the young of all mammals, it is reasonable to hold that it con- 

 tains all the nutrients necessary to sustain the life of the young and 

 that these are arranged in proper proportion. A study of the composi- 

 tion of milk, as given in the following table, 8 will therefore aid in showing 

 the requirements for growth : 



Composition of normal milk and of colostrum milk 



Mineral 



Water matter Protein Sugar Fat 



Per ct. Per ct. Per ct. Per ct. Per ct. 



Cow, normal milk 87.2 0.7 3.5 4.9 3.7 



Ewe, normal milk 80.8 0.9 6.5 4.9 6.9 



Sow, normal milk 81.0 1.0 5.9 5.4 6.7 



Cow, colostrum milk 74 .5 1.6 17 .6 2.7 3.6 



Ewe, colostrum milk 61 .8 1.0 17 . 1 3.5 16 . 1 



Sow, colostrum milk 70. 1 0.9 15. 6 3.8 9.5 



The table shows that milk contains an abundant supply of protein 

 compared with the amount of other nutrients. While the nutritive ratio 

 of dent corn is 1 :10.4, the nutritive ratio of normal cow's milk is 1 :3.9. 

 Ewe's milk and sow's milk are even richer in protein than is cow's milk. 

 Milk is also much richer in mineral matter than are the cereal grains. 

 While only 1.5 per ct. of the dry matter of corn and 3.5 per ct. of the dry 

 matter of oats is mineral matter, the dry matter of cow 's milk contains 

 5.5 per ct. The supply of lime and phosphoric acid, needed in large 

 amounts in the growing skeleton, is especially liberal, these two constit- 

 uents forming about half the total mineral matter. Milk also contains a 

 liberal supply of the fat-soluble vitamine and of the water-soluble vita- 

 mine, both of which are necessary for animals. (104, 120) The sugar 

 and fat in milk furnish energy in concentrated form and also supply 

 nutrients for the formation of the fatty tissues of the body. 



These studies of the composition of milk teach that after weaning, 

 young animals should be given feeds similar to milk in composition; 



T Armsby, Nutrition of Farm Animals, pp. 390-396. 



"Partly from Konig, Chem. Nahrungs- und Genussmittel, Vol. I, 1903. 



