Food Requirements of Animals. 259 



ment for the constructive work is apparently small. It would 

 appear from this that the nutrients serving mainly for fat forma- 

 tion need not come from proteins in the ration, but rather from 

 the fats and carbohydrates. Further, from a theoretical point of 

 view, this would lead us to the conclusion, that for fairly mature 

 fattening animals the nutritive ratio may be wider than that 

 recommended in the German standards. These standards call 

 for a ratio of from 1 :5 to 1 :7 in the various classes of fattening 

 farm animals. 



Kellner, from experiments on oxen, declares that a fattening 

 ration may vary in its nutritive ratio from 1 :4 to 1 :10 without 

 affecting the amount of increase per unit of digestible matter, 

 provided the nutrients supplied above maintenance come from 

 easily digestible feeding stuffs. Armsby, in his standards for 

 fattening steers, provides no additional protein above mainte- 

 nance, only allowing additional therms, which simply represent 

 material for fuel and fat formation. Certain practical feeding ex- 

 periments show that wide rations have been as effective as the 

 narrower ones. On the other hand there are experiments of this 

 class which show more rapid gains when a larger proportion of 

 protein was furnished. Possibly these are to be explained on the 

 basis of increased palatability and variety of nutrients, thereby 

 securing an increased consumption. The proportion of protein 

 was probably a minor factor. When the nutrients supplied secure 

 palatability, ease of digestion and bowel regulation, it is probable 

 that they need not be of very highly nitrogenous character. 



Facts bearing on this point are disclosed in the pig feeding ex- 

 periments at the Rothamsted Station and are appended in the 

 following table. 



The figures in the last column are not the nutritive ratios, 

 which apply to digestible matter, but simply the ratios of nitro- 

 genous to non-nitrogenous matter. The true nutritive ratio would 

 be considerably wider. The results clearly show that 100 pounds 

 of increase were produced with practically the same consumption 



