MAK-UAL OF CATTLE-FEEDING- 157 



Here tlie cliange from a poor ration to one rich in pro- 

 tein cansed at first a very decided gain of liesli. but one 

 tliat rapidly decreased, sinking to about a third of its 

 original amount in less than a week and nearly disappear- 

 ing in nineteen days. 



The contrast between this result and that obtained by 

 Kiihn & Fleischer is exceedingly instructive, and shows 

 anew the importance of a proper proportion of earbhy- 

 drates and fat in the food for the economical production 

 of flesh. 



Carbhydrates equivalent to Fat.— *It is an impor- 

 tant fact for the theory of feeding that the decrease in the 

 protein consumption caused by a given quantity of a carbhy- 

 di-ate is at least equal to, and generally a httle greater than 

 that caused by an equal weight of fat. 



Formerly, when all the non-nitrogenous substances of 

 the food were supposed to be chiefly valuable as fuel to 

 maintain the vital heat of the body, the relative value of 

 fat and the carbhydrates was naturally measured by the 

 amoiuit of heat which equal weights of the two produced 

 when burned ; and it being calculated that one pound of 

 fat produced about 2.5 times as much heat as one pound 

 of sugar or starch, it was assumed that the fat of the food 

 was 2.5 times as valuable as the carbhydrates, and their 

 so-called respiration equivalents were respectively 2.5 and 

 1. So far as they serve for the production of heat, these 

 numbers may represent their relative value, but, as we 

 have seen, they have other important functions ; they 

 not only favor the formation of flesh, but also, as we 

 shall learn, of fat. For the former purpose they are 

 fully equal, weight for weight, to fat, and for the latter 

 nmeh more nearly so than is shown by their respiration 

 et|uivaleiits. 



