6 BULLETIN 507, U. S. DEPARTMENT OF AGEICULTUEE. 



Summary of digestion experiments with chicken fat in a simple mixed diet. 



Experi- 

 ment No. 



Subject. 



Protein. 



Fat. 



Carbohy- 

 drates. 



Ash. 



274 



275 



H. F. B 



D. G. G 



Per cent. 

 61.7 

 65.9 

 75.3 

 65.3 

 62.7 

 69.9 

 76.0 

 69.4 



Per cent. 

 92.9 

 93.8 

 94.6 

 92.0 

 92.3 

 93.9 

 95.3 

 92.2 



Per cent. 

 96.1 

 96.4 

 98.0 

 97.0 

 96.0 

 97.0 

 97.5 

 97.4 



Per cent. 

 62.3 

 69.0 



276 



277 



R.L. S 



O.E.S 



76.1 

 64.1 



290 



H. F. B 



57.9 



291 



292 



D. G. G 



R.L. S 



57.3 

 71.7 



293 



0. E. S 



67.3 











68.3 



93.4 



96.9 



65.7 









The average coefficient of digestibility of the total fat eaten during 

 these tests was 93.4 per cent. As the ether extract of the feces, how- 

 ever, is known to contain metabolic product and undigested fat from 

 the basal ration, which though nearly so was not absolutely fat free, 

 a correction has been appUed in the case of this fat and the others 

 studied to determine the average digestibihty of total fat consumed. 

 Digestion experiments with the basal ration as the only source of fat 

 have been reported in connection with the earher animal fat experi- 

 ments, from which it was concluded that 9.89 per cent of the total 

 weight of water-free feces is made up of metaboUc products and undi- 

 gested fat from the food/ which latter must have been an insignifi- 

 cant quantity, since the total amount in the diet was so small. 

 Subtracting the quantity represented by this percentage from the 

 total ether extract of the feces, a value is obtained more nearly repre- 

 senting the weight of unutihzed fat. The corrected value for the 

 digestibility of fat then becomes 96.7 per cent. 



GOOSE FAT. 



In the United States goose fat is used as such only to a very limited 

 extent and chiefly among those of foreign birth or parentage who 

 adhere to special food customs. 



Owing to the impossibiUty of obtaining goose fat in quantity from 

 local dealers, an unusually fat or ''stall-fed" goose was purchased. 

 It weighed 27.5 pounds, 13 pounds of fat being obtained when the fat 

 was cut away from the flesh and rendered in the usual way. The 

 goose fat, which at room temperature (about 20° C.) is a soft, pale- 

 yellow, granular solid, tended to separate into two layers on stand- 

 ing — an upper, oily layer, and a lower, more or less soUd layer. By 

 using freshly rendered fat, rancidity was avoided, which is likely to 

 occur on keeping, perhaps owing to the 0.7 to 3.5 per cent of soluble 

 fatty acid which the fat contains. 



As regards previous work with this fat, Amschink ^ conducted an 

 experiment of four days' duration with a dog weighing 8 kilograms, 

 in which an average of 50 grams, containing 70 per cent of oleic 



1 U. S. Dept. Agr. Bui. 310 (1915), p. 20. 2 Ztschr. Biol., 8 (1890), pp. 443, 444. 



