THE COMPUTATION OF RATIONS 697 



roughage may predominate, because it is usually relatively 

 cheaper and can supply the required amount of feed in a bulk 

 which the animal can consume. 



3. METHOD OF COMPUTATION l 



The examples given on the following pages are intended simply 

 as illustrations of the method of using the tables of the Appendix 

 and not as model rations. Limitations of space forbid the 

 multiplication of examples, but the reader who grasps the 

 method will have no serious difficulty in applying it to his 

 own conditions, while facility will be acquired with surprising 

 rapidity by practice. It will be observed that the form of 

 these tables and the methods of computation do not differ 

 materially from those which have been used for many years in 

 computing rations on the basis of " digestible nutrients," al- 

 though the significance of some of the figures is different. It 

 may be added that the digestible protein in the tables is true 

 protein that is, it does not include the non-protein. 

 Consequently the percentages, as well as the amounts esti- 

 mated in the rations on succeeding pages, are somewhat 

 smaller than in the older tables. 



800. Total feed required. A bunch of " feeders " 2 to 3 

 years old, averaging 1000 pounds per head and in better than 

 average condition are to be fattened on clover hay and corn- 

 and-cob meal. Such cattle, if of good grade, should weigh 

 1400 pounds each when ready for market and should not re- 

 quire over 200 days to make the gain of 400 pounds. They 

 should therefore make an average gain of 2 pounds per day. 



It may be estimated (Table III) that a gain of i pound live 

 weight, by animals of this grade will require about 3.5 Therms 

 of net energy value in the feed ; for a daily gain of 2 pounds, 

 therefore, the requirement would be 7 Therms. To this must be 

 added the maintenance requirement, which will increase as the 

 animals grow heavier. For the average weight of 1200 pounds 

 it is sufficiently accurate to use the maintenance requirement 

 computed (Table I) for 1250 pounds, viz., 7 Therms. This 



1 The contents of this section are reproduced by permission of the Honorable 

 Secretary of Agriculture, from Bulletin No. 459 of the U. S. Department of Agri- 

 culture, prepared by the writer. 



