NTTKIKNTS ON WHICH FEEDING VALUE IS BASED. 7 



"fat." In this bulletin, however, the tenn "fat" is used to signify the 

 crude product obtained by the ordinary extraction of the dry material 

 with anhydrous ether. 



CARBOHYDRATES . 



In an ordinary analysis of stock foods or similar material all those 

 substances left after the ash, protein, and fat have been determined 

 are included in the term "nitrogen-free extract" and considered as 

 carbohydrate. In materials containing much sugar or when itisdesir- 

 ahle to know the amount of starch, as such, these constituents are 

 determined separately. In cereal grains, excepting sweet corn or 

 saeeharine sorirhums, the amount of sugar is not great and starch is 

 practically the only carbohydrate present. In such cases no sepa- 

 rate determination of these substances is made and the total carbo- 

 hydrate i-> determined only by difference, i. e., 100 per cent less the 

 amount of a-h, protein, and fat combined. 



In many vegetable products, however, a considerable portion of 

 this nit ro'jvn-free e\t ract or carbohydrate remainder consists of fibrous 

 material, -uch afl hull-, -talk-, and the cellulose portions of plants 

 generally. This material, though a true carbohydrate in nature, has 

 a distim-tly different coefficient of digestibility as compared with 

 r or -larch, and must therefore be considered separately. This 

 coarse fibrous portion of vegetable foods is termed "crude fiber," and 

 though only -lightly digest iblc it plays a very important part in 

 duration. It act-* as a dilutant of the more concentrated portions of 



tin- f I. such as starch, necessitates for the whole food thorough 



mastication, and prevents it from becoming too compact; in other 

 \\ords. it keeps the food ma-- porous and open to the action of the 

 digestive llnids. If, however, the amount of this crude fiber or rough- 

 ia in excess, aa in tip arse fodders, the amount of energy 



expended by the animal in -ecurin.i: and digesting the food is so great 

 that it- ultimate nutritive value is correspondingly diminished. 

 That part of the crude liber which is digested has, however, the same 

 nutritive value a- the other carbohydrates, so that, except as regards 

 digestibility, the crude fiber is considered with the other carbohy- 

 drai 



Another carbohydrate suhstanee, in addition to sugar, starch, and 

 crude fiber, is .sometimes considered separately, namely, the pento- 

 Bans. These are compounds related to the sugars, being polymeric 

 forms of five carbon >uirars. Their digestibility and nutritive value, 

 according to Kellner." are nearly the same as those of starch, and con- 

 lently a separate determination is not necessary. When sugar is 

 present in any considerable amount it must be determined separately, 

 as its nutritive value is slightly different from the other carbohydrates. 



Dir Krnuhrung der landwirtschaftlichen Nutztiere, 1905, pp. 88, 153. 



