June i, 1921 
Some Fundamentals of Stable Ventilation 
355 
dividing, therefore, the calories of latent heat of water vapor by 0.587 
the number of grams of water vapor produced is obtained. In the 
foregoing cases the computed amounts per day and per head are as 
shown in Table VI. 
Tablu VI.— Water vapor produced by typical cows per day and per head 
Animal. 
Water vapor. 
Jersey cow producing 20 pounds of milk. 
Gm. 
6 ,947 
7, 782 
8 ,477 
9 , 528 
Jersey cow producing 30 pounds of milk. 
Holstein cow producing 30 pounds of milk. 
Holstein cow producing 45 pounds of milk. 
CARBON DIOXID PRODUCED BY COWS 
Since carbon dioxid is a product of combustion, however slow it may 
be, within the animal body, it is natural to expect that a more or less 
definite relation between the heat production and the output of carbon 
dioxid must exist. From the accumulated data of the heat emission 
and carbon dioxid production by cattle determined directly by means 
of the respiration calorimeter at this Institute, the relation of the car¬ 
bon dioxid produced to the heat given off has been very recently estab¬ 
lished by Armsby, Fries, and Braman (6), who, on comparing the daily 
output of carbon dioxid and the heat production by steers and cows 
for 188 separate days, found that in each case the ratio of the carbon 
dioxid produced in grams to the total heat emission in calories was very 
close to 1 to 2.5, or 0.4, the mean ratio being 1 to 2.495. By making 
use of this factor the amount of carbon dioxid produced by cows in 
grams is computed by simply multiplying the calories of daily heat 
emission by 0.4. 
Tabi,E VII.— Carbon dioxid produced by cows per day and per head 
Animal. 
Carbon dioxid. 
Jersey cow producing 20 pounds of milk. 
Gm. 
6, 525 
7 > 3°9 
7, 962 
8, 949 
Jersey cow producing 30 pounds of milk. 
Holstein cow producing 30 pounds of milk. 
Holstein cow producing 45 pounds of milk. 
HEAT PRODUCTION OP COWS ON MAINTENANCE 
The daily maintenance ration of cattle has been computed by Armsby 
(2) from a number of experiments in terms of metabolizable energy, 
which in this case also represents the total heat production, 10,500 
calories being the average per 1,000 pounds live weight. This, com- 
