MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 6 
as measured directly by the heat production after a longer or shorter period of 
fasting in order to ascertain whether it is possible to determine the basal katabo- 
lism of cattle by a single determination of the heat production in what corresponds 
to the "post-resorptive" state in man. 
Then, in a second season, two or three respiration experiments are to be made 
upon the same cows when in milk at different stages of lactation and on different 
amounts of the standard feed mixture. From the results is to be computed the 
utilization of the energy remaining for milk production after the demands for 
maintenance and for any fattening which may occur have been allowed for on 
the basis of the results obtained upon that identical animal during the first 
season. 
Circumstances beyond the control of the writers prevented taking 
up the experimental work in the order outlined, and the experiment 
here reported takes up only the second problem under the head, 
" Lines of Experiment," "Feed a moderate ration and by means 
of successive respiration-calorimeter experiments trace the variations 
in the distribution of net energy between milk production and body 
gain with advancing lactation. In this way it is hoped to determine 
the quantitative relation between the two forms of production." 
CHANGES IN TECHNIC 
Before the experiments with cows could be outlined in detail a 
number of problems involving changes in the technic of he former 
steer experiments had to be studied. The main question, of course, 
involved a separate collection of the feces and urine in order that the 
digestibility of the ration might be determined. The method of 
milking the animal while in the respiration calorimeter and the collec- 
tion of the excreta in that apparatus also confronted the writers. 
Various devices for the automatic separation of urine from feces 
in the digestion stalls were tested and discarded, and it was necessary 
to depend upon a watchman stationed behind the animals. 
The problem of milking likewise could not be solved by any 
apparatus; and since reconstruction of the respiration calorimeter was 
out of the question, it was necessary to have a man enter the chamber 
to attend to the milking and to apply the necessary corrections to the 
ventilation and to the heat as measured. 
The third problem, and perhaps the most perplexing, was to provide 
a means for the collection of the excreta in the respiration calorimeter. 
Since in this apparatus the feces and urine can not be allowed to 
drop on the floor, or remain exposed to the ventilating air current, 
it is necessary to use a duct to direct the excreta into a proper 
receptacle. This duct must of necessity be comparatively light and 
comfortable for the wearer in order that the animal may lie down and 
get up without difficulty; it must not press upon the udder or milk 
veins or interfere with the milking; and it must fit closely so as not 
to be disarranged by the movement of the animal. One of he writers 
(Fries) devised and made the ducts, a description and sketch of which 
follows. 
The shape and method of attachment of the duct for collecting the 
excreta are illustrated in Figure 1. The duct was made of heavy 
muslin, which was reenforced at the top edge of the side flaps along 
the back with leather straps, and at the lower edge by a double hem. 
It weighed about 1.9 kilograms, and the entire collecting apparatus, 
including collar and attaching straps, weighed 5.9 kilograms. At B 
is a ring, 8 inches in diameter and three-fourths inch wide made of 
steel clock spring. To this ring the upper and lower portions of the 
