June i, 1921 
Some Fundamentals of Stable Ventilation 
35i 
In the second place, it is by no means intended to assert on page 354, 
for example, that every Jersey cow weighing 750 pounds and yielding 
20 pounds of 5 per cent milk will produce exactly 16,313 calories of total 
heat. The computations have been made on the basis of average results 
from which those on an individual animal may vary considerably. This 
is especially true of the fasting katabolism. Moreover, the computations 
have been carried out to the nearest whole calorie so as to record the 
exact results of the calculation. In view, however, of the many possibili¬ 
ties of experimental error involved, it seems very questionable whether 
the last three digits are significant. Probably an estimate to the nearest 
thousand calories—that is, to one therm—would be all that is justified 
and would be sufficiently accurate for the discussion of all ventilation 
problems. 
HEAT PRODUCTION OF CATTUE 
fasting katabouism 
The data for the fasting katabolism of cattle, although obtained by 
indirect methods and not by actually starving the animals, are more 
trustworthy than those for any other species of farm animals for the 
reason that they are more abundant, are concordant, and are based 
largely on experiments with the respiration calorimeter by means of 
which direct determinations of the heat production were made. In 
these experiments the animal is usually fed two different amounts of the 
same feed, and the effect of this on the heat production—that is, the 
decrease of heat production per pound decrease of feed—is determined. 
From this it is estimated how much heat would be produced if all the feed 
were withdrawn—that is, if the animal were reduced to the fasting state. 
The average given by Armsby (3, p. 711 ) for the fasting katabolism 
of cattle per 1,000 pounds live weight is 6 therms, or 6,000 calories, and, as 
the fasting katabolism of animals of the same species has been found to 
be approximately proportional to the two-thirds power of their live 
weight, that of cattle is computed accordingly. Table I gives the fasting 
katabolism of cattle according to their live weight in terms of calories. 
TabIvS I .—Fasting katabolism of cattle 
Live weight. 
Calories, per 
head. 
Live weight 
Calories, per 
head. 
15 ° 
I, 690 
I, OOO 
6, OOO 
250 
2,380 
1,250 
6,960 
500 
3.780 
I, 500 
7, 860 
750 
4,950 
HEAT INCREMENT DUE TO THE CONSUMPTION OF FEED BY CATTUE 
The energy expended by cattle in the increased body activities con¬ 
nected with the digestion and assimilation of many feeding stuffs have 
been determined directly by varying the amount of the feeding stuff in 
