43 



It will be seen that nitrogen-free extract is quite thoroughly assim- 

 ilated, the values ranging from 100 per cent in the case of molasses to 

 17.0 per cent in the case of spelt straw. The high value obtained for 

 the dio-estibilitv of this nutrient in molasses is doubtless due to the 

 fact that carbohydrates exist in it in soluble forms and hence in a con- 

 dition very favorable for assimilation. Possibly the comparatively 

 small amount of crude fiber present in carrots and potatoes accounts 

 for the high digestibility of the starch which makes up the greater 

 part of the nitrogen -free extract of the e feeds. The principal sources 

 of nitrogen-free extract in the ration are the cereal grains and their 

 by-products, and it is interesting to note that the coefficients of digest- 

 ibilit}' of nitrogen-free extract of these materials is high. In the 

 majority of feeding stuffs the crude fiber is not very thoroughl}' 

 digested, the coefficients of digestibilit}' being on an average less than 

 50 per cent. The high value given in the above table for the crude 

 fiber of r3'e is unusual, and should be confirmed b}^ further experiments 

 before it can be accepted. 



The digestibility of the different materials which make up the car- 

 bohydrate group has been recently studied by Weiser and Zalischek" 

 with horses and other farm animals. The following table shows the 

 results obtained with a horse fed different combinations of meadow 

 hay, broom-corn seed, and oats. 



Table .S. — Digestibility of different rdrhohydrates hij a horse. 



Rations. 



Cellulose 



or crude 



fiber. 



8.1 pounds meadow liay and 10.8 pounds broom- Per cent. 



corn .seed ' 45. 6 



7 pounds meadow hay, 6.6 pounds broom-corn 



seed, and 6.6 pound.s oats 



8.3 pounds meadow hay and 7.7 pounds oats 



30.5 

 48.7 





Starch. 



Per cent. 

 84.9 



97.7 

 96.7 



Pento- 

 sans. 



Per cent. 

 53.2 



33.8 

 49.7 



Undeter- 

 mined 

 constitu- 

 ents. 



Per cent. 

 35.8 



34.0 

 57.0 



Total ni- 

 trogen- 

 free 

 extract. 



Per cent. 

 70.3 



70.9 

 72.0 



As will be observed, the starch is much more thoroughly digested 

 than the other carboh^'drates. In all the experiments the values 

 obtained for digestibility of the group, "nitrogen -free extract," were 

 comparatively low. The authors attribute this to the presence of the 

 material called '"undetermined constituents," and advance the opinion 

 that this material does not consist of carbohydrates though included 

 in this group by the ordinary analytical methods. The thoroughness 

 with which the different members of the carbohydrate group were 

 digested by the horse and other farm animals is discussed in the fol- 

 lowing section. 



"Arcli. Pliysiol. [Pfliiger], 93 (1902), p. 98. 



