FATS, CARBOHYDRATES, CRUDE FIBER 11 



especially of rape, turnips and mustard, also in the Umbelliferse (cara- 

 way, fennel, anise, coriander), in juniper berries and in the following: 

 Common milfoil or yarrow, parsnip, garden sage, artemisia or mugwort, 

 calamus, gill-over-the-ground, cow parsnip, tansy (suitable for sheep 

 only), etc. 



V. The Carbohydrates 



The carbohydrates are combinations of carbon, hydrogen and oxygen, 

 in which the last two elements are present in the proportion of 2 to 1, as 

 in water, HgO. , 



The carbohydrates with which we are concerned here usually contain 6 or a mul- 

 tiple of 6 carbon atoms (hexones), although a few contain only five atoms of carbon 

 (pentones). 



From a chemical standpoint the hexones are divided into: 



1. Monosaccharids (grape-sugar group) C6H12O6, represented mainly by grape 

 sugar (glycose or dextrose) ; fruit sugar (fructose or levulose), and galactose. 



2. EHsaccharids, C12H22O11 (cane-sugar group) : Cane sugar (saccharose), milk 

 sugar (lactose), malt sugar (maltose), and raflfinose. 



3. Polysaccharids (CeHioOs) (cellulose or starch group) : Cellulose, starch, 

 dextrin, glycogen, inulin, gum, vegetable mucilage, etc. 



This division, however, is not strictly followed in the study of practical 

 feeding. According to their digestibility we distinguish merely between 

 two groups — crude fiber and nitrogen-free extract. 



1. Crude Fiber 



The term "crude fiber" is applied to all organic nitrogen-free constit- 

 uents of feeding stuffs which remain undissolved after heating the sub- 

 stance in question in a 1.25 per cent solution of sulphuric acid and 1.25 

 per cent solution of caustic potash for one-half hour and extracting with 

 water, alcohol and ether (Henneberg and Weender method). It was 

 formerly believed that the entire cell structure (cellulose together with all 

 ligniform substances) was included in the residue. This supposition was 

 not, however, founded on fact. Thus, only 30 per cent of the organic 

 nitrogen-free cell-wall substance of wheat bran remains undissolved after 

 this treatment, and hulled lupine seed leaves only 6 per cent of crude fiber. 

 The rest is dissolved and is estimated as nitrogen-free extract. 



Crude fiber obtained as above, contains — 



a. Cellulose (CeHio05)xl, which is admixed (incrustated) and pos- 

 sibly, in part, chemically combined with lignin (woody substance), 

 suberin (corky substance), cutin, inorganic salts (especially silicic acid), 

 as well as with nitrogen-containing substances. It is present in the woody 

 parts of plants and in all rough forage (straw, hay, etc.). 



b. Pentosanes. Like cellulose, with which they are frequently ad- 

 mixed, the pentosanes are incrustated with other substances. Chemically 

 the pentosanes (C5H804'lx are regarded as anhydrids of the pentones, as, 

 for example, xylose and arabinose (C5H10O5), just as cellulose, 

 (C6Hio05)x, is an anhydrid-like combination of a hexone (e. g., grape 

 sugar CgHisOe). Externally the pentosanes resemble cellulose, but they 



