Digestive Coefficients of Poultry Feeds, etc. 
5 
The digestive organs of the fowl differ greatly from that of mammals 7 . The food 
passes from the mouth through the pharynx and first portion of the esophagus to the 
crop. The food here becomes moistened, then passes through the second portion of 
the esophagus to the proventriculus where it is soaked in a strong acid solution. It 
then passes into the gizzard and is ground. Thus ground and soaked with acid and a 
ferment pepsin it passes to the duodenum where pepsin digestion is completed. The 
content of the duodenum, about fourteen inches long, is strongly acid. At the lower 
end of the duodenum the bile and pancreatic secretion is poured out and the reaction 
gradually becomes less acid till the caeca, two in number, are reached. The liquid 
flowing into the large intestine, which in the averaged sized hen is about four and one- 
half inches long, now by reverse peristalsis of this portion forces the liquid forward, at 
the same time the caecal valves extend across the mouth of the free portion of the small 
intestine and the content is thus forced into the caeca. This can be demonstrated by 
forcing liquid through a syringe into the large intestine. 
Since the urine and the undigested food accumulate in the cloaca and are voided 
together in the fowl, a means must be used in determining the uric acid content in 
analyses of the excreta of fowls, a factor not present in digestion work in mammals 
since in mammals the urine is eliminated from the body through another channel from 
the undigested food channel or bowel. 
Avian urine has a relatively small water content which rapidly evaporates and 
leaves a white flaky mass of uric acid so commonly seen in the droppings of birds. 
The urea, which makes up the major part of the nitrogenous end-products of mam¬ 
malian urine, is highly soluble, whereas the uric acid making up the bulk of the nitro¬ 
genous end-product in avian urine, is relatively insoluble. The insolubility of the 
uric acid is an important factor in making the uric acid determinations and compli¬ 
cates the test. Mammalian urine is rich in chlorides, phosphates, sulphates, calcium, 
and magnesium. Avian urine contains relatively none of these. The avenue of 
escape for the salts must be in another direction and it is interesting to note that the 
yolk and shell of the egg contains considerable quantities of such salts. 
From a review of literature at hand on this subject it would appear that fowls are 
apparently most efficient in digesting the nutrients in the order of nitrogen-free- 
extract, protein, and fat. They digest relatively little or no fiber. 
THE PROBLEM 
The purpose of the work is to determine the rapidity of digestive processes in the 
fowl and to make sufficient digestive coefficient studies of poultry feeds which, to¬ 
gether with those already available, would be sufficient for a tentative table of digest¬ 
ible nutrients of poultry feeds based on digestion experiments with poultry, to deter¬ 
mine the ash intake and ash outgo and its effect on the digestive coefficients of feeding 
stuffs of poultry, and to determine the fate of grit in the fowl. 
Time Required for Food to Pass Through the Entire 
Intestinal Tract of Fowls 
Fowls of the American breeds were used in these experiments. Only hens were to 
be tested, and birds two to three years of age were selected. 
The birds were kept in small wire coops eighteen inches square with one inch 
chicken netting floor. The coop stood on a tin pan slightly larger than the floor of 
the coop. This pan was to catch the excreta as it was voided. 
Ground feeds such as wheat middlings and corn meal were used in which was in- 
7 Kaupp, B. F., Anatomy of the Domestic Fowl, published by W. B. Saunders Co., Philadelphia, Pa., 
1918 . 
