Nutrition Studies. 75 



mals. C. Voit 1 found that from 1200 to 1500 grams of lean meat 

 per day was required to keep a dog in nitrogen equilibrium while 

 on an exclusive protein diet ; when carbohydrates or fat was added, 

 only from one-half to one-third as much lean meat was needed. By 

 feeding rations exceedingly rich in carbohydrates to animals, some 

 investigators have succeeded in reducing the requirement of nitroge- 

 nous matter to slightly more than the normal nitrogen waste of 

 the body during starvation. At the Pennsylvania Station 2 Armsby 

 found in experiments with steers, covering 70 days, that from 0.4 

 to 0.6 Ib. of digestible protein daily per 1000 Ibs. of live weight was 

 sufficient to maintain the nitrogen equilibrium. Contrary to the 

 observations of some of the earlier investigators, no ill effects fol- 

 lowed this small supply of protein. Wintering cattle on feeds poor 

 in crude protein straw, inferior hay, corn stover, etc. as prac- 

 ticed by many farmers, confirms this finding. During many years 

 of patient study, Haecker of the Minnesota Station found that dairy 

 cows under good care and otherwise liberal feeding would for long 

 periods continue a good flow of milk on a surprisingly small allow- 

 ance of crude protein. After some years of such feeding, however, 

 their vitality was so depleted that they became physical wrecks 

 years before their time. These studies led Haecker to raise his 

 crude protein standard for the dairy cow above his earlier allow- 

 ance. As elsewhere shown, such allowance is, however, still below 

 the Wolff-Lehmann standard. (140) The proportion of digestible 

 protein in a ration should always be large enough to insure the 

 proper digestion of the ration. (60) 



It is a physiological axiom that protein is a cell stimulant. Hence 

 we may conclude that growing animals and those undergoing severe 

 exertion, as cows in milk, horses at hard work, sheep producing 

 wool, and pregnant animals, need considerably more digestible crude 

 protein than the minimum on which they may barely subsist. Tho 

 the protein requirement for such animals is certainly lower than the 

 Wolff-Lehmann standards set forth, it is highly desirable and ulti- 

 mately essential that they be given a liberal supply of digestible 

 crude protein. 



3. Fattening. 



98. The object of fattening. According to Armsby, 3 the accumu- 

 lation of fatty tissue, as such, is only of secondary importance in 



1 Ztschr. Biol., 5, 1869, p. 352. 



2 Principles of Animal Nutrition, 1903, p. 142. 



3 U. S. Dept. Agr., Bur. Anim. Ind., Bui. 108. 



