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 Tule, 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. 
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. J ordan gives the following average 
