004 EXPERIMENT STATION RECORD. 



the food. A more serious error, however, is caused by the crude fiber. 

 This is not digested by the peptic and pancreatic ferments, etc., but by 

 the action of bacteria, and, further, the digestion is not complete. The 

 fermentation of other nitrogen-free bodies is induced by the same bac- 

 teria, and it is probable that protein is also broken down. At any rate 

 the changes which take place are very complicated. Much light has 

 been thrown upon this subject by Kelluer's experiments with steers. 1 

 He found that for maintenance there was required 24,000 calories per 

 day per 1,000 kg. live weight, or 1 calorie per kilogram per hour. In 

 the case of steers fed hay the crude fiber of the feces has a higher carbon 

 content and fuel value than that of the hay fed. It follows, therefore, 

 that the crude fiber digested has a lower fuel value than that eaten. 

 According to Kellner the fuel value of 1 gm. of pure digestible crude 

 fiber furnishes 1.2190 calories, or, in round numbers, about the same as 

 starch (1.18 calories per gram). Further, when hay is fed, the ether 

 extract of the feces has a higher fuel value than the ether extract of 

 the food. Therefore the fuel value of the digestible ether extract is 

 also less than that of the food, being 8.322 calories per gram. Kellner 

 gives the fuel value of the digestible nitrogen-free extract of hay as 

 4.232 calories per gram. These illustrations show that caloriinetric 

 analysis is much more delicate than the ordinary methods of proximate 

 analysis. 



In calculating the fuel value of protein it should be borne in mind, 

 as stated above, that while practically all the amid nitrogen of the food 

 is resorbed, a portion is oxidized in the body and excreted in the urine. 

 Supposing this to have the same heat of combustion as asparagin (.3.511 

 calories per gram), the fuel value of urea at least must be deducted 

 from this in order to estimate its maximum nutritive effect. A gram of 



asparagin yields 0.454 gm. of ureaf ^.^=0.454 J, having a fuel value of 



1.152 calories. A gram of asparagin (containing 0.212 gm. of nitrogen) 

 would furnish 3.511 calories. This quantity, less 1.152, gives 2.36 calo- 

 ries as the available fuel value of 1 gm. of asparagin. These values are 

 at best approximations, but the total error is not great, since such 

 materials constitute only from 1 to 2 per cent of the total material 

 metabolized. 



According to Kelluer's investigations, 3.5 calories per gram repre- 

 sents the physiological nutritive value of digestible organic material of 

 meadow hay of medium quality when consumed by cattle. Such hay 

 has the following percentage composition : Protein 1.393, fat 2.58, crude 

 fiber 27.23, nitrogen-free extract 53.13, ash 7.00, carbon 46.10, and total 

 nitrogen 1.6 per cent. Accordiug to Kellner, the total fuel value of the 

 hay is distributed among its constituents as follows: Albuminoids 10.3, 

 nonalbuminoid nitrogenous material 1.4, nitrogen-free extract 53.8, 

 ether extract 3.6, and crude fiber 30.9 per cent. As noted above, cattle 



1 E. 8. R., 9, p. 107. 



