64 FEEDS AND FEEDING, ABRIDGED 



Requirements for growing animals. — The skin, muscles, ligaments, 

 tendons, and internal organs of animals are almost wholly protein, as 

 is a large part of the nervous system and the organic portion of the 

 bones. During youth, all these parts steadily increase in size, and at 

 the same time much mineral matter is built into the skeleton or is 

 retained in the vital parts of the body cells. It is therefore clear 

 that the rations for growing animals should contain a much larger 

 proportion of protein and mineral matter than is needed in those for 

 maintaining mature animals. After growth is completed, but little 

 storage of protein or mineral matter can take place, for the skeleton, 

 the muscles, and the internal organs have reached full development. 

 However, if an animal is healthy but has poor muscular development, 

 some increase in the size of the muscles can be made thru suitable 

 exercise and an ample supply of protein. Beyond this, the only 

 storage of protein which can occur is in the growth of the nitrog- 

 enous hair and hoofs, and the small amount of protein stored in the 

 fatty tissues. 



We have seen that maintenance rations may consist chiefly of 

 roughage, which furnishes little net energy. On the other hand, for 

 thrifty growth, the ration must be more concentrated (that is, must 

 furnish more net energy) to provide for the energy stored in the 

 growing tissues of the body in the form of protein and fat. 



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 life in the young, and that 

 these are in proper proportion. A study of the composition of milk, 

 as given in the following table,^ will therefore aid in showing the re- 

 quirements for growth. 



Composition of colostrum and normal milk 



..,-., X Nutri- 



Animal and character w-^i^i: Protein Fat Sugar Ash live 



of milk ratio 



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



Cow, colostrum 75.1 17.2 4.0 2.3 1..5 1:0.7 



Cow, normal 87.3 3.4 3.7 4.9 0.7 1:3.9 



Ewe, colostrum 61.8 17.1 16.1 3.5 1.0 1:2.3 



Ewe, normal 80.8 6.5 6.9 4.9 0.9 1 :3.1 



Sow, colostrum 70.1 15.6 9.5 3.8 0.9 1:1.6 



Sow, normal 84.1 7.2 4.6 3.1 1.1 1:2.0 



The first milk yielded by the mother, called colostrum, is thicker 

 anch far higher in protein and often richer in ash than ordinary milk. 

 Colostrum is laxative and highly important for cleansing the alimen- 



iKonig, Chem. Nahrungs- und Genussmittel, Vol. I, 1903. 



