654 EXPERIMENT STA.TION EECOKD. 



BEHAVIOR OF THE CRUDE FIBER AND NITROGEN-FREE EXTRACT 

 IN THE HUMAN BODY. 



In f/eneral. — In sijite of the uncertainties in the determination of 

 crude fiber pointed out in tlie preceding- pages, it is a well-known fact 

 that for years thousands of fodder analyses have been made in which 

 crude fiber and nitrogen-free extract have been determined by the 

 Weende method more or less modified. The question is pertinent as to 

 how the constituents determined in this way behave in the animal body, 

 and especially what x>i'oportion of the nitrogen-free extract and the 

 crude fiber are used by the animal and what portion is excreted 

 undigested. 



Digestion experiments have usually shown that a large proportion, 

 and in some cases nearly all, of the nitrogen-free extract is digested.^ 

 Sometimes, as in the case of leaves, hay, and straw, the figures are low — 

 40 to 70 per cent — but in case of grains (Hour, meal, etc.) they reach 90 

 per cent and over. These coefficients have been obtained by digestion 

 experiments with animals (cattle, horses, sheep, swine, geese, etc.). 



Method of Stufzer and Isherf. — A method by which the digestibility 

 of nitrogen-free extract could be determined in a shorter time than by 

 the natural method was considered very desiriible, and accordingly 

 one was worked out by Stutzer and Isbert.^ In this they attempted 

 to imitate the digestion in the body with the aid of artificially prepared 

 ferment solutions, using the ferments of the saliva (ptyaliir), stomach 

 (pepsin), and abdominal salivary gland (])ancreas) Dui^licate samples 

 of 2 gm. each of the feeding stuff were first extracted with ether, and 

 then heated to boiling with water. After cooling, 200 cc. of the ptyalin 

 solution was added and digested for 2 hours at 37 to 40° C (or 25 cc. 

 diastase solution was added and digested for 2 hours at 00 to 05° C). 

 Tlie solution was then filtered through an asbestus filter, the residue 

 washed, and digested for 12 hours at 37 to 40° C. with 250 cc. of a 

 solution of pepsin from pig's stomach, care being taken that the solu- 

 tion contained 0.1 per cent of hydrochloric acid throughout tlie diges- 

 tions. This was filtered thro'ngh asbestos, washed, and the residue 

 Including asbestus digested for 3 hours at 37 to 40° C. Avith 100 cc. of 

 alkaline pancreas solution. 



In this way, by the action of ferments (ptyalin or diastase, pepsin, 

 and pancreas) the i:)ortion of the carbohydrates which is digested in 

 the animal body was dissolved, and there remained the undissolved 

 I)ortion of the nitrogen-free extract and the crude fiber (i. e., the cellu- 

 lose and its accompanying substances, lignin), the undissolved portion 

 of the protein substances, a part of the ash constituents, and a consid- 

 erable quantity of asbestos. 



'Dietrich and Kouig, Die Znsammeiisetznng nnd Verflauliclikeit der Fnttprmittel. 

 Berlin, 1891, part 2, pp. 1070-1127, 1280-1339. 



- Ztschr. pliysiol. Chem., 12 (1888), p. 72; Centbl. agr. Cliem., 17 (1888), p. 112. 



