DIGESTIBILITY OF THE GRAIN SORGHUMS. 7 



for changes in the composition of the apples and potatoes taking place 

 during the preparation for eating. 



The two common methods for determining the coefficients of diges- 

 tibility of any single food contained in a mixed diet are, applying the 

 factors obtained in a direct determination of the availability of the 

 basal ration (digestion experiments with the basal ration alone), and 

 using factors for the digestibility of the basal ration which were 

 determined by averaging the results of earlier experimental data. In 

 the experiments reported in this paper the latter method was used. 

 The digestibility of the bread alone was estimated by assuming the 

 following values for the digestibility of the accessory food materials: 

 The protein of potatoes, 83 per cent; the protein of milk and butter, 



97 per cent; the protein of fruit, 85 per cent; the carbohydrate of 

 potatoes, 95 per cent; and the carbohydrate of milk and cane sugar, 



98 per cent. These assumed values are not absolute, but are close 

 approximations based on the results of a large amount of reliable 

 experimental work. 1 



The method of estimating the digestibility of the bread alone is 

 indicated by the following equations: 



[Weight of protein in accessory food materials] X [Percentage of 

 undigested protein in each] = [Protein in feces from food other than 

 bread. 



[Total protein in feces] — [Protein in feces from food other than 

 bread] = [Weight of undigested bread protein.] 



[Weight of protein in bread] — [Weight of undigested bread pro- 

 tein] -f- [Weight of protein in bread] = [Estimated percentage of avail- 

 ability of bread protein.] This value, and a similarly computed one 

 for the digestibility of the bread carbohydrate, are given in the tables 

 and are taken as the coefficients of availability of the protein and 

 carbohydrate in the grains. Since the quantity of lard used in mak- 

 ing the bread was greatly in excess of the fat content of the grain, it 

 seemed relatively unimportant to estimate the digestibility of the fat 

 of the grain. In view of the fact that the diet contained accessory 

 foods supplying considerable quantities of both carbohydrate and 

 fat, the digestibility of these constituents from the total diet should 

 be approximately the same as has been found for the ordinary mixed 

 diet, 2 namely, 97 and 95 per cent. 



DIGESTIBILITY OF THE SORGHUM MEALS PREPARED AS BREADS. 



DIGESTION EXPERIMENTS WITH HARD KAFIR BREAD. 



The first series of tests with kafir bread included seven 3-day 

 experiments with four different subjects. The bread formed a part 

 of a simple mixed diet containing milk, fruit (oranges), and sugar. 

 As noted on page 4, this bread was thin and had thick, hard crusts 



1 Connecticut Storrs Sta. Rpt. 1899, p. 104. 6 Connecticut Storrs Sta. Rpt. 1901, p. 245. 



