88 FEEDS AND FEEDING 



tained in the protein and fat which was digested had gone to form 

 fat in the body, there still remained a large amount of deposited fat 

 which could only have come from the carbohydrates of the food. These 

 conclusions were confirmed in later experiments by Kellner, 26 also with 

 oxen. In these later trials it was shown that 100 Ibs. of digested starch 

 or digested fiber yielded about 24.8 Ibs., and 100 Ibs. of digested cane 

 sugar only 18.8 Ibs., of body fat. 



Tho no experiments have yet been carried on to show that body fat 

 may be formed from pure pentosans, it is certain that these carbohydrates 

 may aid in its formation. Kellner 27 fed oxen straw in which pentosans 

 furnished 33 per ct. of the energy. The large deposits of fat which 

 followed must have come in part from the pentosans of the food. 



128. Fat from protein. When a liberal protein diet supplies the animal 

 with more energy than is necessary for its maintenance, not only may a 

 part of the excess protein be deposited in the body as flesh, but the non- 

 nitrogenous portion resulting from the cleavage of protein may be con- 

 verted into either body fat or glycogen. Since body fat may be derived 

 from the carbohydrates, and since glucose and glycogen may be formed 

 from the proteins, it is reasonable to hold that body fat may be formed 

 from the protein of the food. Demonstration of the direct formation 

 of body fat from food protein is difficult, as it is almost impossible to 

 induce animals to consume any large quantity of pure protein food. 

 The consumption of protein must be relatively large to maintain the 

 nitrogen equilibrium of the body, and so usually but a small excess avail- 

 able for the formation of fat remains above body requirements. 



Investigations by Cramer 28 with cats, and by Voit 29 and Gruber 30 with 

 dogs which were fed large amounts of lean meat, show that the protein 

 it contained must have been the source of the fat which was stored in 

 their bodies during the trials. 



Herbivora the ox, horse, sheep, etc. cannot be fed exclusively on 

 protein, since such feeding causes intestinal disorders. Kellner, 31 ex- 

 perimenting with steers, added wheat gluten, which is principally com- 

 posed of vegetable proteins, to a ration which was already causing a 

 considerable deposition of fat. The feeding of 100 Ibs. of protein caused 

 the deposition of 23.5 Ibs. fat in addition to the fat due to the basal 

 ration. 



129. The ration for fattening. Since the fattening of mature animals 

 consists mainly in the storage of fat, there is no demand for a large sup- 

 ply of food protein. While the Wolff-Lehmann standards (Appendix 

 Table IV) advise nutritive ratios of 1 :5.4 to 1 :6.5 for mature fattening 



28 Land. Vers. Stat., 53, 1900, pp. 1-450. 

 "Landw. Vers. Stat,, 53, 1900, pp. 1-450. 

 28 Ztschr. Biol., 38, 1899, p. 307. 



29 Jahresber. Tier-Chem., 22, 1892, p. 34. 

 Ztschr. Biol., 42, 1901, p. 407. 

 "Landw. Vers. Stat., 53, 1900, p. 452. 



