CLEANING MILKING MACHINES 1 
By L. H. Burgwald, 
Assistant Market Milk Specialist , Bureau of Dairying , United States Department 
of Agriculture 
INTRODUCTION 
This paper gives the results of tests made for the purpose of com¬ 
paring heat, chlorine, and salt and chlorine as agents for sterilizing 
milking machines. The word sterilizing is here used not in its tech¬ 
nical meaning, but in the popular sense of denoting treatment which 
supposedly kills the organisms present with such a degree of complete¬ 
ness as to render the apparatus sanitary. In view of the various 
methods advocated for tne sterilization of milking machines, 2 some 
comparative studies on three of the methods most generally used 
were considered desirable. 
METHODS OF STERILIZING 
Three single units were used in these tests. The units were washed 
and sterilized by the writer personally during the entire period, 
each unit receiving exactly the same treatment except in the steri¬ 
lizing. 
Immediately after milking, each unit was rinsed by drawing clean 
cold water through by vacuum, then it was washed with a brush in 
hot water (110° to 120° F.) containing washing powder, and then 
rinsed in clean hot water. Each unit (consisting of teat cups, claw, 
and milk tubes) was taken apart and thoroughly washed after each 
fourth or fifth milking. The units were sterilized as follows: 
One unit was placed in a 5-gallon crock containing a chloride 
of lime solution (1 part available chlorine to 5,000 parts water), and 
one in a 5-gallon crock containing a saturated brine solution and 
chloride of lime (1 part available chlorine to 5,000 parts brine). 
These two units remained in the solutions for 24 hours or longer 
between milkings, except for the short period when they were used 
twice a day. Fresh solutions were made up after using for 8 or 10 
milkings in cold weather, and after 4 or 5 in warm weather. The 
third unit was placed in hot water at 160° to 165° F. for 20 to 30 
minutes just before milking, being kept in clean cold water the rest 
of the time. 
A stock solution was made by dissolving a 12-ounce can of chloride 
of lime in 1 gallon of water and filtering into a glass bottle or jar. 
This was covered and kept in a cool, dark place. Sterilizing solutions 
were made by adding 1 ounce of stock solution to every gallon of 
water used. 
i Received for publication October 21, 1924; issued September, 1925. 
* Ruehle, G. L. A., Breed, R. S., and Smith, G. A. milking machines. N. Y. State Agr. Exp. Sta. 
Bui. 450: 113-181, illus. 1918. 
Blodgett, W. K., and Brew, J. D. directions for cleaning and care of milking machines. N. Y. 
State Col. Agr., Cornell Ext. Bui. 43: 39-44, illus. 1914. 
Hart, G. H., and Stabler, W. H. experiments with and practical application of heat steril¬ 
ization FOR ALL PARTS OF MILKING MACHINES. JOUT. Dairy Sci. 3: 33-51. 1920. 
Burgwald, L. H. cleaning milking machines. U. S. Dept. Agr. Farmers’ Bui. 1315, 16 p., illus. 
1923. 
Journal of Agricultural Research, 
Washington, D. C. 
( 191 ) 
Vol. XXXI, No. 2. 
July 15,1925 
Key No. 1-2 
