FOODS — ANIMAL PRODUCTION. 



1073 



constituting that portion of the ration which serves for production, is 

 shoAvn in the followino- table: 



FJiysiolixjical imtrUire value of different feedhig stuff's. 



Feeding stuffs. 



Gluten protein 



Peanut oil 



Starch 



"Straw-like material 



Molasses No. 1 



Molasses No. 2 



Meadow hay No. 5. . . 

 Meadow hay No. 6. . . 



Oat straw . . " 



Wheat straw 



In ration for 

 mainte- 

 nance. 



Calories. 

 4, 958 

 8, 821 

 3,760 

 3,651 

 3,829 

 3,462 

 3,553 

 3, 728 

 3,747 

 3, 327 



In amount avail- 

 able for production. 



Per cent. 

 45.2 

 56.3 

 58.9 

 63.1 

 68.9 

 68.3 

 40.2 

 42.8 

 37.6 

 17.8 



Calorics. 

 2,241 

 4,966 

 2,215 

 2,304 

 2,255 

 2, 365 

 1,428 

 1,596 

 1,409 

 592 



The authors calculate that fat is formed from starch according to 

 the following equation: 100 gm. starch + 38. (39 gm; oxygen = 3. 17 gm. 

 methan4-23.1: gm. water + 88. 77 gm. carbon dioxid + 23.34 gm. fat. 

 The results of the tests are believed to show further that protein is to 

 be regarded as a source of fat. The digestible crude fiber in the straw 

 freed from encrusting material is stated to possess a nutritive value not 

 at all inferior to that of digestible starch. The furfurol-yielding sub- 

 stances of a ration are regarded as not inferior to starch or cellulose 

 for the formation of fat. The easily digestible cellulose of extracted 

 rye straw, in the authors' opinion, protected protein and rendered it 

 a\'ailable for the formation of muscular tissue. 



The following are enumerated as the causes of the loss of energy 

 when organic substances are digested, absorbed, and converted into 

 body tissue: (1) The labor of chewing and digesting, including that 

 required for the absorption of water to moisten the food for solution 

 and the action of enzyms in the feeding stuffs; (2) the formation of 

 methan by fermentation which, as shown by the authors' observations, 

 is limited to the nitrogen-free material and crude fiber and does not 

 concern the protein and fat; (3) destruction of food by the large num- 

 ber of micro-organisms in the intestinal tract, further aided by the 

 length of time the material remains in the intestinal tract of rumi- 

 nants; (-1) the incompletely oxidized material which is excreted in the 

 urine; and (5) the molecular rearrangement of absorbed material when 

 it is converted into body substance, a change which probably requires 

 a considerable energy expenditure. 



Furtlier, the productive value of feeding stuffs depends not alone, 

 according to the authors, upon its content of digestible nutrients, but 

 is materially affected hy the physical properties of cell tissue and the 

 presence of undigestible so-called encrusting substances. All such 

 conditions which increase the labor of chewing and digesting or the 

 sohition and ab.sorption of the nutrients enclosed in cells, diminish the 



22065- No. 11 -6 



