18 



Table 4. — Amoinil, xpirijii- (jrarihi, ami iiilroyai of vritte from digei^linn p.rj}eriweyits 

 with Oregon aiul Oklohouia wheat bread — Continued. 



Whciii'f obtKJiR'il. 



Kxperiment No. 487: 



First day 



Sucoiid day 



Third day 



Experiment No. 488: 



First day 



Second dav 



Third day' 



P^xperiment No. 489: 



First day 



Second day 



Tliird day 



Experiment No. 490: 



First day 



Second day 



Third day 



Expcriiiu'iit No. 491: 



First day 



Second dav 



Third day'. 



Experiment No. 492: 



First day 



Second dav 



Third dav 



Total 

 amount 

 voided. 



Grams. 

 1 

 1 



Specific 

 gravity. 



1,195 1 

 1,3.=>4 IV «1. 

 1,924 I 



745 1 



804 !^ 



1,467 I 



026 



1,099 



1,203 



721 



1,518 

 l,lil2 

 1,753 



.507 

 1,019 

 1,012 



• 1.028 



a 1.024 



"1.026 



a 1.028 



1,060 ,1 

 1,070 \ a 

 1,112 i| 



1.023 



Nitrogen. 



Per cent. 

 nl.47 



a 2. 08 



al..57 



nl.62 



nl.81 



'11.46 



« Composite sample. 



EXPERIMENTAL METHODS. 



The method followed in makino- the digestion experiments was simi- 

 lar to that explained in detail in a former bulletin." A simple diet of 

 bread and milk was eaten, each material being consumed ad libitum, 

 but the amount taken at each meal weighed and recorded. The 

 digestibility of the nutrients of the total diet was determined from the 

 quantity of each in the food and feces. The digestibility of the nutri- 

 ents in the bread alone was computed by assuming coefficients of 

 digestiliility for the nutrients of the milk, as explained beyond. 



The bread was made by the short process of fermentation — that is, 

 with a large proportion of yeast. Comparatively large amounts of 

 salt and water were used in mixing the dough, but neither milk nor 

 .shortening. For each experiment two bakings were made, the sub- 

 jects preferring bread twenty-four hours old to fresh bread. 



The digestibility of the total diet of bread and milk was calculated 

 from the difference between the total nutrients in the food consumed 

 and those in the feces.^' The digestibility of the bread alone was cal- 



«U. S. Dept. Agr., Office of Experiment Stations Bui. 85. 



6 It will be observed that, although the factor 5.70 is more nearly correct for the 

 calculation of the percentage of protein in cereals from the percentage of nitrogen 

 determined, the factor 6.25 has been used in these experiments. The same factor 

 has been used for mil"k protein, in which case it is correct. The use of this factor 

 for cereals also is merely for convenience in the computations of the digestibility of 

 the protein. If different factors were used for the protein of different foods, the 

 same differences in factors would have to be observed in estimating protein of feces, 

 and this would involve complicated computations. Since the coefficient of digesti- 

 bility would be the same whichever factor is used, provided the same factor is used 

 for protein of both food and feces, the factor 6.25 has been used uniformly for 

 convenience. 



