THE OCCURRENCE OF LACTASE IN THE ALIMENTARY 
TRACT OF THE CHICKEN 1 
By T. S. Hamilton and H. H. Mitchell, Division of Animal Nutrition , Illinois 
Agricultural Experiment Station. 
INTRODUCTION 
In the experiments reported in the preceding paper (p. 597) it was found 
that lactose, fed to hens, does not appear in the excreta in appreciable 
quantities until excessive amounts are administered—a finding thoroughly 
in agreement with our present knowledge of sugar-feeding in human 
beings. Since lactose is assimilated from the alimentary canal of chickens, 
and since assimilation of disaccharids is normally preceded by hydrolysis 
into monosaccharids, lactase would be expected to be present in some 
part of the alimentary tract. However, the possibility of bacterial fermen¬ 
tation accounting for the disappearance of lactose must be considered. 
Previous investigations are not entirely in agreement in regard to the 
presence of lactase in the alimentary tract of the fowl. Portier (4 2 ) in 
1898, using the osazone method for the detection of monosaccharids 
formed by the action of the enzym extracts on a lactose solution, found 
no indication of lactase in the intestines of birds. This was confirmed a 
year later by the extensive investigations made by Weinland (6) who, 
using the polarimetric method, found no indication of lactase in the intes¬ 
tines of fowls. He states, however, that the enzym is produced in the 
intestines of fowls if they are fed on milk and lactose. Bieri and Portier 
(j), using the duck in their experiments, found in one case, on feeding 
lactose and milk, that the intestines produced lactase, but a second experi¬ 
ment failed to confirm the first. Plimmer ( 2 ), in an extensive investigation 
on the subject of adaptation of the intestines to lactose, found that the 
intestines of fowls are naturally free of lactase and, furthermore, that 
lactase was not produced when lactose and milk were fed for long periods 
of time. Plimmer used Allihn’s reduction method for the estimation of 
the degree of hydrolysis of a lactose solution produced by the enzym 
extracts. In a recent study on the distribution of enzyms in the ali¬ 
mentary canal of the chicken, however, Plimmer and Rosedale (3) found 
lactase to be present in the crop, but absent in the proventriculus and 
intestines. The presence of the enzym was determined by incubating 
at 37 0 C. a 4 per cent lactose solution with portions of boiled and unboiled 
extracts of the various organs for two days or more, removing the pro¬ 
teins, and determining the reducing sugars by reduction of Fehling’s 
solution. The observed difference in reading between the boiled and 
unboiled solutions indicated whether or not hydrolysis by lactase had 
occurred. In the present investigation a similar study has been made. 
This inquiry did not extend, however, to the detection of lactase in the 
1 Received for publication Jan. 26, 1924. 
3 Reference is made by number (italic) to “ Literature cited,” p. 608. 
(605) 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXVII, No. i 
Feb. 23, 1924 
Key No. Ill.—13 
