286 BEGINNINGS IN ANIMAL HUSBANDRY 



slightly over, are required, as compared with 2J/ recom-* 

 mended in the Wolff table. These standards, however, are 

 a guide to intelligent feeding. One is not expected to 

 measure out to each animal an exact amount of dry matter 

 and nutrients to just agree with the standards, but rather 

 to so combine the feeds that they will furnish the balanced 

 ration reasonably well. 



Other feeding standards than Wolff's have been pro- 

 posed. Kellner, a noted German student of animal nutrition, 

 has proposed a standard in which starch is the unit of value. 

 Armsby, a leading American investigator, has offered a 

 standard which is based on the energy or heat value of food 

 referred to in the preceding chapter. He has prepared a 

 table showing the values of certain feeds in protein and net 

 digestible energy, expressing the energy value in therms. 

 He has also prepared other tables showing what is required 

 as a maintenance standard for horses, cattle, and sheep, 

 and also for growing cattle and sheep. The important 

 feature of the work of the more recent investigators is that 

 they figure that each animal requires a certain amount of 

 nutriment for maintenance, after making allowances for 

 losses of energy in digestion and assimilation. They then 

 add to the nutrients of maintenance enough more to meet the 

 special body needs, to produce growth, milk, wool, or energy 

 for external work. These changed views on standards have 

 been made possible by the use of the digestion calorimeter 

 in which animals as large as full-grown cattle are placed. 

 With this apparatus, the experimenter can measure up the 

 losses from the body through respiration and through heat 

 and moisture from the body surface. Such information as 

 this was not available at the time Wolff introduced his feed- 

 ing standards. Thus far, but little practical application of 

 */he energy standard of value has been made by feeders 



