THE UTILIZATION OF LACTOSE BY THE CHICKEN ‘ 
By T. S. Hamilton, Division of Animal Nutrition , and L. E. Card, Division of 
Poultry Husbandry , Illinois Agricultural Experiment Station 2 
The value of milk, in its various forms, as a poultry feed has been 
clearly established, the high quality of its proteins and minerals being 
its chief assets. The present investigation was undertaken primarily for 
the purpose of determining whether or not lactose, the carbohydrate of 
milk, was utilized by the chicken. It is not always realized that lactose 
represents approximately 38 per cent of the total solids and approxi¬ 
mately 30 per cent of the energy of whole milk, while the total proteins 
contain but 26 per cent of the solids and approximately 20 per cent of 
the energy of whole milk. In some commercial milk preparations the 
percentage of lactose is much higher; whole milk powder contains 34 to 
41 per cent, skim milk powder 48 to 54 per cent, and secwa, or dried whey, 
contains approximately 74.5 per cent lactose and 14.2 per cent soluble 
albumin (5). 3 From a practical point of view the carbohydrates of a 
ration usually seem of less importance than the protein because of the lower 
relative cost of the former, but a knowledge of the amount and utiliza¬ 
tion of the carbohydrates present is necessary in order to formulate the 
most desirable and economical ration for a particular purpose. Thus a 
knowledge of the amount and degree of utilization of the lactose in milk 
is of practical importance to the science of poultry feeding. The ques¬ 
tion is also of theoretical interest because at no stage in the life of the 
chicken is milk, or any other substance containing lactose, a part of its 
natural diet, and therefore the utilization of lactose, which normally 
requires the presence of a lactase, might rightfully be questioned on 
teleological grounds. 
The literature available on the subject of the utilization of lactose by 
the fowl is very meager. In addition to investigations on the adaptation 
of various digestive organs to lactose, only two studies have been found 
dealing directly with the question. Shaw (7), in a study of digestion in the 
chick, concluded that lactose was not digested and, further, that it acted 
as an irritant to the gastrointestinal mucosa. Chicks fed from birth on 
milk alone died on the third day and the contents of no part of the intes¬ 
tinal tract gave a positive test for monosaccharids with Barfoed’s reagent. 
That lactose was present was shown by preparing the phenyllactosazone 
crystals. Plimmer and Rosedale (6), on the other hand, claim to have fed 
chickens from birth to a period exceeding three months on a diet con¬ 
taining lactose. Failure to find reducing sugars in the excreta was taken 
to indicate the assimilation of lactose. 
EXPERIMENTAL DATA 
In determining the utilization of lactose, the reducing sugars present 
in the excreta of hens fed on an ordinary cereal diet and on a diet con¬ 
taining variable amounts of lactose were estimated. Seven experiments, 
1 Received for publication Jan. 26,1924. 
8 The writers desire to thank Dr. H. H. Mitchell for many helpful suggestions and advice regarding 
certain procedures followed in this work. They are also indebted to C. I. Bray for some preliminary 
analytical work in connection with the sugar methods used. 
3 Reference is made by number (italic) to "Literature cited," p. 604. 
Vol. XXVII, No. S 
Feb. 23,1024 
Key No. Ill.-i* 
ouraal of Agricultural Research, 
Washington, D. C. 
( 597 ) 
