730 Starch Equivalents of Feeding Stuffs, [dec, 



ing that 100 lb. of starch yield a quarter of their weight in fat 

 (i.e., 24*8, or, in round numbers, 25 lb.), it is seen that in 

 order to produce 8 lb. of fat it would be necessary to feed 

 32 lb. of starch under the same conditions; thus 100 lb. of 

 hay gave as much fat as 32 lb. of starch, and the starch 

 equivalent of the hay becomes 32. 



A further example is furnished in the case of 100 lb. of 

 barley which yielded 18 lb. of fat, and converting this into 

 the starch equivalent by multiplying by 4 the figure 72 is 

 obtained. 



It must not be concluded from the above that the starch 

 equivalent applies only to foods that contain starch. The 

 starch equivalent is really only a standard with which other 

 foods can be compared, as the relation that exists between 

 starch and body fat has been accurately ascertained. Foods 

 such as meat meal (with a starch equivalent of 89*9), cow's 

 milk, linseed cake, gluten meal, &c, have their respective 

 starch equivalents, although they contain little or no starch 

 at all. 



The published starch equivalents have been derived almost 

 without exception from experiments conducted in Germany, 

 and so they primarily apply only to the foods and cattle of that 

 country, or, more strictly considered, to the food and animal 

 employed in each particular case. There is little reason, 

 however, to suppose that British feeding stuffs would be 

 found to differ very much, and as no provision is made in 

 this country for repeating these determinations, those that 

 are available must be accepted. 



Determination by Calculation. — The starch equivalent of a 

 food can also be determined by calculation if the following 

 values are assigned to the nutrients : — 



1 part digestible protein = 0 94 parts starch equivalent. 



1 ,, -fat (in coarse fodders, chaff, roots and their bye- products) = 



1 '91 parts starch equivalent. 

 1 fat (in grains and their bye-products, except oil seeds) = 



2' 12 parts starch equivalent. 

 1 fat (from oil seeds and oil cakes) = 2 '41 parts starch equivalent. 



1 nitrogen-free extract substances (carbohydrates) and crude fibre 



together = i'oo parts starch equivalent. 



The calculation is then easy, although two points have to 

 be borne in mind ; firstly, that the digestible protein may 

 contain some amide-like substances, which are sure to be 

 digestible, but which are not regarded as having the feeding 



