BREEDS OF BEEF CATTLE 



301 



The growing animal also requires a sufficient supply of digesti- 

 ble protein for maintenance and to supply material for new growth. 

 No very systematic study of the latter requirement has yet been made, 

 but from the results of a considerable number of practical feeding 

 trials it is possible to make a fairly satisfactory estimate of the total 

 amounts of digestible protein which should be contained in the ra- 

 tions of cattle and sheep at different ages to insure satisfactory 

 growth. These estimates are contained in the following table. They 

 are expressed in pounds per head and include the maintenance 

 requirement. As a matter of convenience, the table also contains 

 the estimated energy values required per head for normal growth, 

 and it thus constitutes a set of approximate feeding standards. In 

 their use the weight rather than the age of the animal should be the 

 controlling factor. 



Estimated Requirements Per Day and Head. 



FOR GROWING CATTLE. 



FOR GROWING SHEEP. 



a Including the maintenance requirement. 



No satisfactory data for colts are available, while, as noted else- 

 where, knowledge of the relative values of feeding stuffs for swine is 

 somewhat deficient. 



Requirements for Fattening. The foregoing data refer to what 

 might be called normal growth, in which the animals are kept in a 

 good thrifty condition, but do not become fat. If any considerable 

 fattening is desirable, somewhat heavier rations must be given in 

 proportion to the amount of gain made, because the increased gain, 

 in fattening animals consists to a very large extent of fat, and there- 

 fore means the storing up by the animal of more reserve energy. 

 For fairly mature fattening animals such, for example, as the 2 

 to 3-year-old steers which are commonly fattened in the corn belt 

 probably 3.5 therms per pound of gain in live weight is a fair allow- 

 ance, although more appears to be often used in practice. As yet no 

 corresponding data are available for the fattening of growing ani- 

 mals, as, for example, in the production of the so-called baby beef. 

 It is not probable, however, that any larger amount of protein is re- 

 quired in such fattening than in feeding simply for normal growth, 

 so that the additional food given for fattening may, from this point 

 of view, consist largely of nonnitrogenous material, i. e., carbohy- 

 drates and fats. It is to be noted, however, that an excess of these 

 material* in the ration tends to cause less perfect digestion, and also 



