256 PRODUCTIVE FEEDING OF FARM ANIMALS 



Growth and Fattening. Before considering the method of 

 feeding to be followed in the production of different kinds of steers, 

 it will be necessary to discuss briefly some phases of the general 

 laws of beef production. Beef production, as production of meat in 

 general, includes two more or less distinct processes : Growth and 

 fattening. The growth of animals takes place from birth to ma- 

 turity, and consists essentially in an increase in the protein tissues 

 of the body and the bone structure, etc. (p. 20). At the same time 

 there is an accumulation of body fat that will vary according to 

 the character and quantity of feed eaten. The production of pro- 

 tein tissues can be modified to a certain extent by the feed, but it 

 appears to be mainly a function of the animal and is determined 

 by its individuality and breeding. Growth is most active in the 

 young, and gradually diminishes as the animal grows older, until 

 it practically ceases in the mature animal. 



Fattening, on the other hand, can take place at any age; it 

 accompanies the production of protein tissues in the growing ani- 

 mal, especially if this is fed in liberal amounts with fattening feeds, 

 but, as a rule, it goes on most rapidly from the time the animal has 

 made its growth, when there is a greater surplus of feed materials 

 available after the maintenance requirements of the body have been 

 met. The fattening process is, therefore, in the main determined 

 by the amount of feed which the animal receives and can digest in 

 excess of that required for maintenance and growth, or for main- 

 tenance only, in the case of mature animals. 



The processes of growth and fattening may, as suggested, be 

 going on at the same time in the animal body. A calf or yearling, 

 if gaining in weight, is always laying on fat, and a two-year-old 

 may mature to some extent while being fattened. The fattening 

 process improves the quality and flavor of the meat and makes it 

 tender and juicy; this comes through a deposition of fat between 

 the muscle tissue, and an increase of the extractives of the meat. The 

 accumulation of fat about the internal organs and below the skin is 

 incidental to the improvement of the meat by the fattening process 

 and represents a certain value, but animals are fattened primarily 

 to increase the tenderness and palatability of the meat, and not for 

 the purpose of obtaining large amounts of internal fat and thick 

 layers of fat about the body. 13 



Composition of Increase in Fattening. The results of early 

 experiments at the Rothamsted station by Lawes and Gilbert show 

 that an increase in body substance, even in young animals, consists, 

 to a large extent, of pure fat. Jordan gives the following average 



'a See Mo. Res. Bui. 39. 



