Animal Nutrition. 



57 



animals than in lean ones. This partially explains why the 

 fattening of animals grows more difficult during the last stages of 

 the fattening period. (565) 



81. Feeding protein alone. Large quantities of protein protect 

 the body fat from oxidation, as will be seen by the following 

 experiment by Pettenkofer and Yoit 1 with a dog fed exclusively 

 on fat-free meat, and kept in a respiration apparatus: 



Feeding fat-free meat to dog in respiration apparatus Pettenkofer 



and Voit. 



The increased feeding of fat-free meat caused an increased con- 

 sumption of protein, but the decomposition of fat was checked by 

 feeding 1,500 grams (about 3.3 pounds) of fat -free meat per day, 

 and where larger quantities of fat- free meat were fed the animal 

 was able to lay on fat. The consumption of protein was at the 

 same time greatly decreased. 



82. Feeding both protein and fat. The following experiments 

 by Pettenkofer and Yoit 2 show the influence of different quanti- 

 ties of fat and meat on the decomposition of protein and fat in 

 the body of a dog. Comparing the data given in the table, we 

 notice the influence of the feed in the different combinations. 

 Where the same quantity of protein was fed in the form of meat, 

 with varying quantities of fat, the gain in body fat was larger 

 when the largest quantities of fat were fed, and the gain was, as 

 a rule, proportional to the quantity fed. With a liberal supply 



'Voit, ibid., p. 116. 



2 Zeitschr. f. Biologie, IX, p. 30; Voit, Physiologic, p. 134. 



