202 III. DIGESTIBILITY OF FATS 



as 60.5 mg. per gram dried feces. The high value obtained for the calcium- 

 low and magnesium-low diets is to be attributed to the very low weight 

 of feces which resulted, rather than to any increase in the excretion of 

 metabolic lipid. 



(4) Methods for the Study of the Digestibility of Lipids in Dogs 



Procedures similar to those used in the digestibility tests with human 

 subjects and with rats have likewise been employed in the tests with dogs. 

 Most dogs can be trained to consume a synthetic diet, such as that pro- 

 posed by Cowgill, 6 in which the test fat can be incorporated in the ration 



Table 4 

 Composition of Diets Used in the Digestibility Tests with Dogs" 



Composition of diets, % 

 Food component Diet 1 Diet 2 Diet 3 



Commercial casein 20.0 20.0 20.0 



Sucrose 35.0 35.0 35.0 



Dextrin 12.2 12.2 12.2 



Margarine fat 6 18.3 18.24 15.3 



Cod liver oil (U.S.P.) 5.0 5.0 5.0 



Cellu flour" 2.5 2.5 2.5 



Salt mixture* 2.0 2.0 2.0 



Dried brewer's yeast* 5.0 5.0 5.0 



Isopropyl citrates plus vehicle 7 . 06 



Stearyl citrates" — — 3.0 



a Data from C. E. Calbert, S. M. Greenberg, G. Krvder, and H. J. Deuel, Jr., Food 

 Research, 16, 294-305 (1951). 



b Without additives. 



e Added for bulk. Preparation of cellulose obtained from Chicago Dietetics Supply 

 House, Chicago, Illinois. 



d L. G. Wesson, Science, 75, 339-340 (1932). 



e Strain G. Anheuser-Busch Brewing Co., St. Louis, Mo. 



' Chiefly monoisopropyl citrate in 1 : 1 mixture of mono- and diglycerides. 



" Chiefly distearyl citrate. 



at a constant level. A dietary regimen of this nature was employed by 

 Calbert et al. 7 for a study of the absorption of margarine fat and the ex- 

 tent to which it was altered by the simultaneous administration of iso- 

 propyl citrate or stearyl citrate. The composition of the diets fed is given 

 in Table 4. 



8 G. R. Cowgill, J. Biol. Chem., 56, 725-737 (1923). 



7 C. E. Calbert, S. M. Greenberg, G. Kryder, and H. J. Deuel, Jr., Food Research, 

 16, 294-305 (1951). 



