June i, 1921 
Some Fundamentals of Stable Ventilation 
353 
cases, such as may be found in good practice. The typical weights and 
rations upon which the computation of the heat emission by dairy cows 
has been based are those suggested, at the request of Mr. Clarkson, by 
Prof. C. H. Eckles, of the University of Minnesota. 
Table III .—Typical live weights arid rations 
Breed. 
Live 
weight. 
Daily milk yield. 
Daily ration. 
Pounds. 
Percentage 
of fat. 
Com 
silage. 
Alfalfa 
hay. 
Grain 
mixture." 
Additional 
linseed 
meal. 
Pounds. 
Pounds. 
Pounds. 
Pounds. 
Pounds. 
Jersey. 
900 
20 
5 *° 
30 
8 
6 
Do. 
900 
30 
5 -o 
30 
8 
9 
I 
Holstein. 
1,250 
3 ° 
3-5 
40 
10 
6 
Do. 
1,250 
45 
3-5 
40 
10 
10 
I 
a Composed of ground com 4 parts, wheat bran 2 parts, linseed meal 1 part. 
COMPUTATION OF THE} HEAT PRODUCTION OF DAIRY COWS 
To compute, for example, the daily heat production by the typical 
Jersey cow giving 20 pounds of milk daily, it is only necessary to add 
to the fasting katabolism of a cow weighing 900 pounds the heat incre¬ 
ment due to the ration consumed. According to Table I the fasting 
katabolism of a cow weighing 1,000 pounds is 6,000 calories, while that 
for one weighing 750 pounds is 4,950 calories. From these figures the 
fasting katabolism of a cow weighing 900 pounds may be estimated with 
sufficient accuracy by simple proportion as being 5,580 calories per day. 
It remains to figure out the heat increment caused by the consumption 
of feed. By using the average percentages of dry matter in the feeds as 
given in Henry and Morrison’s tables ( 10 ) it is found that the amounts 
of dry matter contained in the ration are: 
In corn silage. 7.9 pounds. 
In alfalfa hay. 7.3 pounds. 
In grain mixture. 5.4 pounds. 
Since the grain mixture consists of 4 parts of corn, 2 parts of wheat bran, 
and 1 part of linseed meal, the heat increment per pound of dry matter 
of the grain mixture (Table II) is: 
1/7(583.3 X 4 + 533.9 X 2 +547.9 X 1) =564-1 calories. 
The heat increment per pound of dry matter of alfalfa hay is 530.3 
calories, and that of com silage is assumed to be 483.1 calories—that is, 
the figure corresponding to com stover—since no figure for corn silage is 
available. From these figures the total heat increment caused by the 
ration is obtained as follows: 
Com silage... 483. 1X7. 9= 3, 816 calories. 
Alfalfa hay.53°. 3X7. 3= 3, 871 calories. 
Grain mixture. 564. 1X5. 4= 3, 046 calories. 
Total heat increment 
ro, 733 calories. 
