127 



of other foods fed with it. Column iii. gives the total nitrogen 

 reckoned as albuminoid nitrogen. Column vii. gives the total 

 nitrogen reckoned as albuminoid nitrogen which is actually 

 digested. Column xi. gives the nutritive ratio, or the ratio of 

 digestible albuminoids to the digestible carbo-hydrates, fibre, 

 and fat. 



The nutritive ratio is arrived at by multiplying the diges- 

 tible fat in column x. by 2'5 (1 Ib. fat being equivalent to 

 about 2*5 Ib. of carbo-hydrates), this product being added to 

 the sum of the digestible carbo-hydrates and fibre in columns 

 viii. and ix. The sum thus obtained is divided by the amount 

 of digestible albuminoids in column vii., and the result is the 

 nutritive ratio. 



The nitrogen present in foods is not all in the albuminoid 

 form. In mature foods, however, most of the nitrogen is in 

 this form. In young grass about one-quarter, and in roots about 

 one-half of the nitrogen present is non-albuminoid, and hence 

 not so valuable for feeding purposes. Potatoes have about 60 

 per cent, and mangels about 40 per cent, of their nitrogen in 

 the albuminoid form. 



It should be explained here that the albuminoid ratio is 

 obtained by adding the total fats, multiplied by 2'5 to the 

 total soluble carbo-hydrates (the fibre being omitted in this 

 case), and dividing the sum by the total nitrogen reckoned 

 as albuminoids. The true albuminoid ratio is obtained in the 

 same way, except that only the true albuminoid nitrogen is 

 reckoned as albuminoids. 



The total nitrogen in a food multiplied by 6'25 gives 

 approximately the total nitrogen reckoned as albuminoids. 



How the digestible constituents are calculated 



These are obtained from the results of elaborate feeding experi- 

 ments with ruminants,* the amount of each constituent actually 



* Ruminants include cattle and sheep. Horses have considerably less power 

 than these to digest bulky fodders containing large amounts of fibre, and such 

 foods are quite unsuitable for pigs. Foods rich in fat are not suitable for 

 horses, and they digest this only to a limited extent. 



