191 1.] Starch Equivalents of Feeding Stuffs. 729 



Table A. 



I kilogram (2 '2 lb.) protein gave 235 grams (8*4 oz.) fat 



1 ,, (2*2 lb.) starch ,, 248 ,, (8*8 oz.) ,, 



• 1 ,, (2*2 lb. ) cane sugar ,, 188 ,, (67 oz.) 



1 (2-2 lb.) cellulose ,, 248 ,, (8*8 oz. ) ,, 



1 ,, (2*2 lb.) fat ,, 474— 598 ,, (167— 2I'I oz.) ,, 



Still more interesting is the fact that from the results of a 

 very large number of actual trials conducted by Kellner 

 and his associates, the conclusion can be drawn that the 

 digestible nutrients in ordinary .feeding stuffs behave as they 

 do when fed in a pure form, as has been stated above. 

 Naturally, the availability of each food must be taken into 

 consideration, but where the contained nutrients are of full 

 value the gain to the animal would be the same as though 

 corresponding quantities of protein, starch, sugar, crude fibre, 

 or fat had been given. 7'his important fact connects theory 

 with practice and enables anybody to say what is the value of 

 certain foods when the amount of digestible nutrients and also 

 the availability are known. As it has been, as we believe, 

 .accurately determined that starch, protein, &c, give rise 

 under certain conditions to a fixed amount of fat, and that 

 the nutrients in the common feeding stuffs behave in a similar 

 manner, but are influenced as regards quantity by the greater 

 or lesser difficulty which the animal body experiences in 

 making them available, it is possible to assign to each food 

 its equivalent in starch, which, of course, is a measure of 

 the amount of fat which that particular food would give if 

 used for an animal which was already on a maintenance 

 diet. 



Determination of Starch Equivalents. — The starch equiva- 

 lents of foods can be determined in two ways, either by 

 direct feeding trials with full-grown animals in which known 

 weights of the feeding stuff are fed and the increase in body 

 weight (fat) is noted, or by assigning a starch value to each 

 nutrient, and then multiplying the amount of digested mate- 

 rial (ascertained by chemical analysis and digestibility trials) 

 by the factor appropriate to each. 



Determination by Experiment. — Considering first of all 

 the estimation of the starch equivalent by direct experiment, 

 -the case may be taken of where the addition of ioo lb. of 

 meadow hay to the maintenance ration of an adult ruminant 

 was found to result in a gain to the body of 8 lb. of fat. Know- 



