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MAY BE OF GREAT SERVICE DURING THE PRESENT LABOR SHORTAGE
IF USED ON FARMS WHERE 20 OR MORE COWS ARE KEPT.
SELECTING A MACHINE.
Use the same business judgment that you would in buying other machines. If the agents tell you the same stories that they have told to us, many of them should be accepted with a grain of salt. The longer a machine has been in successful operation, the surer you can be that it is a mechanical success. A record of three years of successful operation is none too long to make sure that a machine is worth buying; and the record should have been made independently of the manufacturer.
As a general rule, the simpler the construction of a machine, the more likely it is to be a success. This statement applies especially to teat cups. If of complicated construction, it is very difficult to keep them bacteriologically clean. Do not accept statements that machines which allow stable air to pass into the machine with the milk are failures because they are unsanitary. Our recent tests show that not more than 1 or 2 bacteria per c. c. are added to the milk in this way.
OPERATING A MACHINE.
Even if you have installed a machine which is as good as there is to be had, you may be sure it will not be a success on your farm unless you operate it properly. It is as necessary to use judgment and care in milking a cow by machine as by hand. The cow is not a machine and never can be made over into one. If you fail to make a success of a machine which others have used successfully for three or more years, the probabilities are that the trouble is with try to discover what is wrong. We should be glad to pass on to you any information of value which we have gained from our ten years of experience with machine milking.
CAN YOU GET AS MUCH MILK BY MACHINE AS BY HAND? Yes. Bulletin 353 answers this question. The records there given are by far the most extensive that have ever been gathered.
Reprint of Circular No. 54, May 10, 1917.
KEEPING THE MACHINE BACTERIOLOGICALLY CLEAN.
This is just as important as operating it properly. Very few farmers who are using machine milkers are keeping them bacteriologically clean. Where this is not done, the milk usually has a germ content of 50 to 10,000 per c. c. as it enters the teat cups and leaves them with a germ content of 200,000 to 5,000,000 per c. c.
Such milk sours quickly and is not fit to be sold as market milk, or for butter or cheese making.
The pail can be kept clean in the same way that any milk pail is kept clean. Steam or scald it and dry it out thoroly. Rubber parts cannot be kept clean in this way and they should be kept in a disinfectant solution. Various germicides have been tried out for the purpose and several of them are useful. Very few have been tried out thoroly enough to justify recommending them. The one which we have found to be the most useful and which we know will give satisfaction if directions are followed is ordinary chloride of lime (bleaching powder) purchasable at any drug store. This is equally as good as or better than the patent preparations on the market frequently recommended by manufacturers of milking machines, for all of which you pay double prices.
PREPARATION OF DISINFECTANT SOLUTION.
Do not buy more than one or two 12 oz. cans of chloride of lime at any time and do not accept any in broken or rusted packages, or any that is moist. It should be a dry powder if it is fresh and of good strength. Prepare a stock solution by adding all of the powder in a can to a gallon of water in a pitcher or tall glass jar. This will give you a greenish colored liquid with a heavy, white sediment of lime.
Fill a second crock holding 20 to 30 gallons with water and add one pint of the stock solution to this twice a week. Double this quantity will do no harm. The solution in the big crock loses strength quickly on using and in a few days will become useless if the new chloride is not added. It is advisable to add enough salt to the crock to make a strong brine as this keeps the solution from freezing in cold weather, and brine is of itself a good solution in which to keep the teat cups (see Bulletin 353). The salt, however, is not necessary if attention is given to keeping up the strength of the chloride solution. This solution may be used indefinitely if its strength is maintained by adding fresh chloride of lime solution as directed.
PROCEDURE FOR CLEANING.
Immediately after each milking prepare three pails. Fill Pail 1 with clean cold water, Pail 2 with hot sal soda water, and Pail 3 with clean hot water. While the teat cups are still attached to the
machine immerse them in these pails successively, at the same time sucking the water thru them. Then take the teat cups and stanchion hose and either suspend them or immerse them in the solution in the large crock. Care should be taken when putting the tubes into the solution to make sure that all air bubbles are out of the tubes and that they are completely immersed.
Neither rubber nor properly made metal parts are injured by the solution recommended. In case you have trouble from corrosion of the metal parts, it will show you that the manufacturer from whom you have purchased your machine has given little thought to making his machine a sanitary as well as a mechanical success. Our machines handled as above outlined have been found by many tests to be as near sterile as it is practicable to make them. Milk drawn thru machines cared for in this way is cleaner and freer from bacteria than hand drawn milk.
Once a week the rubber teat cups should be taken apart completely and each part thoroly cleaned. No disinfecting solution will take the place of cleaning.
Just before beginning to milk, suck a pail of clean water, either hot or cold, thru all of the teat cups. Otherwise traces of the disinfectant may be carried over into the milk. Even if this does happen and traces are carried over, harmless compounds are formed like some already present in the milk. The action is such that it would be necessary to add large quantities of the disinfectant if anyone should attempt to use it fraudulently as a preservative in milk. If this is done the milk has such an unpleasant odor and taste that it is unsalable. Chloride of lime is also a very valuable disinfectant for use in caring for unfiltered city water supplies and large quantities of it are used in this way.
DO MILKING MACHINES SPREAD OR CAUSE GARGET? It is frequently claimed that they do but there is no satisfactory evidence upon which to base such a claim. Thus far very few records have been secured upon which to base an intelligent opinion. We have had no more trouble with garget in the Station herd in the case of machine-milked cows than in the case of hand-milked Cows. Moreover, such records as we have been able to gather in the course of milk control work where we examined the milk from 36-40 farms (eight of which have used or are using machines of four different makes) does not indicate that garget is spread any worse in the machine-milked than in the hand-milked herds. In the course of two years four herds have been badly affected with garget. Two of these were hand milked, two machine milked. Machine milking was discontinued on one farm partly on account of the garget. On the other farm machine milking was continued and the garget infection cleared up fully as quickly as it did on the farms
where hand milking was practiced. Further information secured under carefully controlled conditions must be obtained before it will be clear whether or not this claim that garget is spread by machine milking is true. There is no evident reason why it should be so.
The labor shortage has caused and will cause machines to be put upon the market which are intended to sell rather than to give satisfaction. Deal only with responsible firms whose business reputation is worth more to them than the few thousand dollars which can be gained by selling a few milking machines.
N. B.-The above is a preliminary report of experiments still in progress. A more complete report will be published in bulletin form when the work is completed.
Department of Bacteriology.
R. S. BREED, Bacteriologist.
H. J. CONN, Associate Bacteriologist.
G. L. A. RUEHLE, Assistant Bacteriologist.
J. D. BREW, Assistant Bacteriologist.
JOHN BRIGHT, Assistant Bacteriologist.
TABLE OF CONTENTS.
I. Soil flora studies, Parts I to V. II. What is meant by quality in milk? III. The number of bacteria in milk. IV. The control of bacteria in market milk by direct microscopic