170 THE SCIENTIFIC FEEDING OF ANIMALS 



origin, like tankage, etc.) are completely metabolized, i.e., are 100 percent 

 available, this fact should be taken into consideration in calculating the starch 

 value and the difference should be adjusted. The available energy or "value" 

 of the various classes of feeding stuffs as well as that of the individual feeding 

 stuffs is subject to considerable variation. This is due to differences in digestibil- 

 ity, the amount of work required in the act of digestion, losses from fermentative 

 processes in the digestive canal, etc. Thus, in potatoes 100 percent of the digestible 

 nutrients are available and metabolizable ; in small field beets only 72 percent; poor 

 meadow hay 49 percent, and good meadow hay 78 percent. The nutrients in the 

 seeds of the grain-bearing grasses (cereals), Leguminosae and oil-producing plants 

 are 90 to lOO percent metabolizable. Most of the by-products of the sugar, starch 

 and distilling industries are somewhat less metabolizable (about 80 to 90 percent). 

 Milling by-products show a very considerable variation in this respect (70 to 1()0 

 percent), and the various chaffs, shells, hulls, etc., are still lower in "value." In 

 general all varieties of straw are inferior in this respect (30 to 50 percent), and 

 the same may be said of poor grades of hay and green forage in the woody stage, 

 while young succulent grasses approach the grains in the facility or completeness 

 with which their digestible nutrients are metabolized. 



Kellner standardized the energy values of the various feeding stuffs. The objec- 

 tion might be raised that this is impossible in view of the variety of purposes aimed 

 at, breed, age, manner of preparation, mixture of feeding stuffs, their content in 

 mineral matter, stimulating substances, etc. It is known from practical experience 

 that these factors influence results. Though these weak points are admitted, they 

 arc of secondary importance when the positive value of Kellner's method is con- 

 sidered in connection with the former custom of basing feeding rations almost 

 wholly upon the chemical composition of the ingredients. Furthermore, the diffi- 

 culties met with in Kellner's method may be expected to be gradually overcome as 

 our experimental knowledge is increased. 



Instead of the formerly used "nutritive ratio," which indicated the 

 relative amount of digestible nitrogen-free nutrients and digestible^ crude 

 protein, Kellner expresses the proportion of digestible pure albumen 

 (albumen ratio) to that of the digestible nitrogen-free extract. 



In order to reduce the ratio to terms of two figures and thus simplify 

 calculations, the fat- is multiplied by 2.5 (old method) or by 2.2 (Kell- 

 ner's method) and added to the carbohydrates. 



The nutritive ratio of meadow hay which contains 5.4 percent digestible crude 

 protein (of which 3.8 percent is digestible albumen), 1.0 percent digestible fat and 

 25.7 percent nitrogen-free extract is determined thus: 



5.4: IX 2.5 -f 25.7 

 =5.4:28.2 

 = 1 : 5.2 

 The albumen ratio of the same feeding stuff is determined as follows: 



3.8: IX 2.2 -f 25.7 

 =3.8:27.9 

 =r 1:7.3 



The nutritive ratio is referred to as "medium" when the proportion of crude 

 protein to nitrogen-free extract is expressed by 1 :5 to 6., narrow when expressed 

 by 1 :2 to 4, and wide when expressed by 1 :8 to 12. 



Those nutrients which are taken up in excess of the requirements of 

 the body for maintenance and which are digested and absorbed are de- 

 posited in the body either as fat (or albumen, muscle) or they are used 

 up in the production of muscular energy, milk, wool, etc. 



The standardization of feed, or the calculation of a ration, for the 



6The word "total" and not the word "digestible" was probably intended to be used here by tbe 

 author. — Translator. 



