402 The Feeding of Animals 



butter or eggs resulting from its use, and calculate 

 the ratio of any one of these to the actual nutrients 

 consumed, or we may ascertain the ratio of food con- 

 sumption to the edible dry substance in the various 

 animal products. The latter is the important ratio to 

 consider if we are seeking to learn how we can most 

 efficiently apply farm crops to the sustenance of the 

 human family. 



This study of food economics requires a knowledge 

 of several factors. In the first place, we must have 

 the information coming from feeding experiments, 

 where a careful record has been kept of the kind and 

 amount of food consumed and of the weight of the 

 resulting growth, milk, eggs, or what not. This in- 

 formation must be supplemented by a knowledge of 

 the digestibilit}^ of feeding stuffs, of the ratio between 

 the live animal or other gross product and the com- 

 mercial products and of the composition and propor- 

 tion of edible material supplied by the commercial 

 article. For instance, we find it takes, on the average, 

 7.40 lbs. of digestible organic substance in the ration 

 to produce one pound of growth in a steer, and we 

 have learned by slaughter tests that the average per 

 cent of carcass for 97 animals was 61.4, and by the 

 butchers' and chemists' analyses, that the carcass 

 contains an average of 33.2 per cent of edible dry 

 matter. From these data it is easy to calculate that 

 12 lbs. of digestible food are needed for the growth 

 of one pound of carcass or 36.3 lbs. for the growth 

 of one pound of edible beef solids. 



The following tables give the data upon which is 



