UNITED STATES DEPARTMENT OF AGRICULTURE 
In Cooperation with the 
Pennsylvania State College 
DEPARTMENT BULLETIN No. 1281 
Washington, D. C. 
December 19, 1924 
RELATIVE UTILIZATION OF ENERGY IN MILK PRODUCTION AND 
BODY INCREASE OF DAIRY COWS 
By J. August Fries, Assistant Director, Winfred Waite Braman and Donald 
C. Cochrane, Associates in Animal Nutrition, Institute of Animal Nutrition 
of Pennsylvania State CoV 
CONTENTS 
Page 
General scheme for experiments on milk pro- 
duction 2 
Changes in technic 3 
Plan of the experiments 4 
Animals 5 
Rations 5 
Digestion experiments 6 
The respiration calorimeter 7 
Preparation of feed and feces samples for an- 
alysis 8 
Methods of analysis 8 
Live weights and rations... 9 
Composition of feed and feces 9 
Apparent digestibility 10 
Hair and scurf removed by brushing 11 
Milk 11 
Methane 12 
Page 
Apparent digestibility of rations by improved 
method 13 
The respiratory gases 14 
Correction for milker 14 
The nitrogen and carbon balance 15 
Metabolizable energy 15 
Heat emission... 20 
Heat production 22 
Net energy of feed for body gain and milk pro- 
duction 24 
"Drying-up" period 28 
Effect of advance in lactation 30 
Standing and lying 30 
Summary 32 
Literature cited 33 
Appendix 34 
This bulletin covers the first of a series of cooperative experiments 1 
with the respiration calorimeter on the metabolism of dairy cows, 
in accordance with an agreement between the Dairy Division, Bu- 
reau of Animal Industry, United States Department of Agriculture, 
and the Institute of Animal Nutrition of the Pennsylvania State 
College, and as recorded in the program of work of the department 
for the fiscal year 1915-16. Previous work with the respiration 
calorimeter had been with steers, and although much remains to be 
done in connection with the fundamental problems of feeding for 
meat production, the increasing importance of the dairy industry of 
the United States led the late H. P. Armsby, then Director of the 
Institute of Animal Nutrition, to plan this series of experiments 
with milk cows. 
In connection with this report of the first experiment the general 
scheme as outlined by Director Armsby is given in full as follows. 
Although changes in experimental procedure have been made as our 
knowledge of the problem has increased, the project plan has been 
1 To Director H. P. Armsby belongs the credit for the planning and inception of the experimental pro- 
gram. For the execution of the plan of experiment the responsibility rested largely with the senior writers 
but the success of this venture was in no small measure due to the faithful work of K. K. Jones, J. W. Park, 
J. E. Mensching, J. E. Isenberg, and E. W. Schmidt, and to other members of the staff of the institute, 
who assisted the writers in various capacities. 
The writers also desire to express their appreciation to E . B . Forbes, director of the institute, for his kindly 
criticism and suggestions which have been invaluable in the preparation of these data for publication. 
