UNITED STATES DEPARTMENT OF AGRICULTURE 
u.s. 
Id cooperation with the 
Pennsylvania State College /rro"**^ 
DEPARTMENT BULLETIN NirlkC. 
Washington, D. C. 
December, 1924 
RELATIVE UTILIZATION OF ENERGY IN MILK PRODUCTION 
AND BODY INCREASE OF DAIRY COWS 
J. AUGUST FRIES, Assistant Director, WINFRED WAITE BRAMAN and 
DONALD C. COCHRANE, Associates in Animal Nutrition, Institute of 
Animal Nutrition of Pennsylvania State College 
General Scheme for Experiments on Milk Production . 
Changes in Tecbnic . 
Plan of the Experiments 
CONTENTS 
Page 
. . 2 
Rations 
Digestion Experiments 6 
The Respiration Calorimeter 7 
Preparation of Feed and Feces Samples for Analysis .... 8 
Methods of Analysis 8 
live Weights and Rations 9 
Composition of Feed and Fetes 9 
Apparent Digestibility 10 
Hair and Scurf Removed by Brushing 11 
Milk 11 
Methane 12 
Page 
. 13 
, 14 
. 14 
, 15 
, 15 
Apparent Digestibiity of Rations by Improved Method 
The Respiratory Gases 
Correction for Milker 
The Nitrogen and Carbon Balance 
Metabolizable Energy 
Heat Emission 20 
Heat Production 22 
Net Energy of Feed for Body Gain and Milk Production . . 24 
" Drying-up " Period 28 
Effect of Advance in Lactation 30 
Standing and Lying 30 
Summary 32 
Literature Cited 33 
34 
WASHINGTON 
GOVERNMENT PRINTING OFFICE 
1924 
