2o6 UTILISATION OF FOOD B V THE ANIMAL [chap. x. 



the comparison fair, the non-nitrogenous food con- 

 stituents must be reckoned in terms of carbohydrates 

 by multiplying the fat by 2-3 and adding it to the 

 carbohydrates and digestible fibre ; the ratio of the sum 

 of these constituents to the digestible protein is known 

 as the albuminoid ratio. If the albuminoid ratio is 

 to be a figure of the slightest value in judging of a 

 food ration, it must be calculated on the digestible 

 constituents only and not on the analytical composition 

 simply, as is so often done. An albuminoid ratio of 5 : i or 

 less is said to be narrow ; when it approaches 10 : i or 

 12: I it is called wide. The ratio is of comparatively 

 little importance in connection with the cases we have 

 just been discussing — animals at work and not increasing 

 in weight ; but when we are dealing with animals which 

 are growing and increasing in weight, which, therefore, 

 especially in the younger stages, are adding to the amount 

 of body protein they contain, or again with animals 

 which are secreting milk, the albuminoid ratio becomes 

 of more value in forming a judgment of a ration. This 

 most important side of feeding will be considered in the 

 following chapter. 



