Issued January 29, 1907. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY. BULLETIN No. 92. A. D. MELVIN, CHIEF OF BUREAU. 8 Sf : MILKING MACHINE AS A FACTOR IN DAIRYING. I (A PRELIMINARY REPORT.) 7 = I. PRACTICAL STUDIES OF A MILKING MACHINE. BY C. B. LANE, B. S., Assistant Chief, Dairy Division, Bureau of Animal Industry. II. BACTERIOLOGICAL STUDIES OF A MILKING MACHINE. BY W. A. STOCKING, JR., M. S. A., Bacteriologist < Storrs Agricultural Experiment Station, Professor of Dairy Bacteriology , Connecticut Agricultural College. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1907. Issued January 29, 1907. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY BUU.I-TIN No. 92. A. D MHI.VIN, Oin> .,>. BUREAU. THE MILKING MACHINE AS A FACTOR IN DAIRYING. (A PRELIMINARY REPORT.) PRACTICAL STUDIES OF A MILKING MACHINE. BY C. B. LANK, B. S., ssistant Chief, Dairy Dii'isiou, Bureau of Animal Industry. II. BACTERIOLOGICAL STUDIES OF A MILKING MACHINE. BY W. A. STOCKING, JR., M. S. A.. Bacteriologist , Starrs Agricultural Experiment Station, Professor of Dairv Bacteriology, Connecticut Agricit I tn ral Co liege. WASHINGTON: GOVERNMENT PRINTING OEEICE. ! c >07. BUREAU OF ANIMAL INDUSTRY. Chief: A. IX MEI.VIN. Assistant Chief: A. M. FARKINGTON. Chief C/erl:- K. B. JONES. Biocliemic Dieision: MARION DORSET, chief. Dairy Dirisiun: Ki>. II. WEHSTER, chief; C. B. LANE, assistant chief. Inspection Division: HICK P. STEDDOM, chief; U. (7. HOTCK, associate chief; MORRIS WOODEN, assistant chief. Pathological Dirislon: JOHN R. MOHLER, chief. Quarantine Dieision: RICHARD W. HICKMAN, chief. Division of Zoology: BRAYTOX II. RANSOM, chief. Experiment Station: F. C. SCHROEDER, superintendent; AY. E. COTTON, assistant. Animal Husbandman: (!EORGE M. ROMMEL. Editor: JAMES M. PICKENS. DAIRY DIVISION. Chief: Fd. II. Webster. Assistant Chief: C. B. Lane. Assistant: Win. Hart Dexter. Butter investigations: C. F. (Tray, cliemist, in charge; C. W. Fryhofer, assistant; E. A. McDonald, W. S. Sinarzo, W. J. Credicott, market inspectors. Market mill: investigations: C. B. Lane, assistant chief, in charge; R. II. Shaw, chemist; (ieorge M. Whitaker, Fllis M. Santee, Ivan C. Weld, assistants. Cheese investigations: C. F. Doane, expert, in charge. American varieties: John L. Sammis, chemist: Jay W. Moore, expert maker. European varieties: Charles Thorn, mycologist; Arthur W. Dox, cliemist; T. W. Issajeff, expert maker. Southern dairy investigations: B. H. Rawl, expert, in charge; II. N. Slater, Duncan Stuart, J. A. Conover, S. E. Barnes, J. W. Ridgway, J. F. Dorman, assistants. Building and management investigations: B. D. White, expert, in charge; IT. II. Parks, architect; W. J. Latimer, Joseph A. Lockie, assistants. Dairy laboratories: L. A. Rogers, bacteriological chemist, in charge. INSI'ECTIOX STAFF. Henorated butter factories: M. W. Fang, 510 Northwestern Building, Chicago, 111., in charge. liennrated butter markets: Levi Weils, Laceyville, Pa., in charge. Inapcctors: Robert McAdam, 510 Northwestern Building, Chicago. 111.; (ieonre M. Whitaker, Washington, D. C. ; F. A. McDonald, Seattle, Wash. Deimtij inspector*: S. 1!. AYillis, Boston, Mass.; R. A. McBride, J. II. Barrett, (i Harrison street, New York, N. Y.; II. P. Olsen, St. Paul, Minn. LETTER OF TRANSMITTAL. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY, Wash! ny ton, D. in the series of this Bureau. The investigations will be continued and further results may Ite reported later. The experimental work which is the basis of this bulletin was con- ducted in August, 1905. but owing to unavoidable delays the manu- script has not been ready for publication until now. Respectfully. A. P. MELVIN, C '/i lf Bv.r<-/. Hon. JAMES WILSON. ^t-rt'ctni'i/ of Ayr!c>dtur<-. 3 CONTENTS. 1. PRACTICAL STTIUKS OF A MILKING MACHINE. Page Introduction !l Some milking machines in use 10 A foot-power milker 11 A power milker : 11 A milker designed for either hand or power \'2 The machine used in the investigations 1 - Cost of equipment for machine milking !''> Different kinds of power which may he utili/ed b'^> Experiments in which hand and machine milking were compared 14 Experiment No. 1 14 Time required for hand and machine milking compared 17 Yield of milk from hand and machine milking compared 18 Thoroness of hand and machine milking compared -0 Experiment No. '1 20 Time required for hand and machine milking compared 24 Yield of milk from hand and machine milking compared '24 Thoroness of hand and machine milking compared 1'5 Quality of the milk 1'ti General considerations. -7 Effects of milking machines upon the cows '27 Adjusting the machines to the cows l'S Practicability of using machines f< >r large and small herds -!' How the general introduction of the milking machine would affect the dairy industry ... L'i* Suggestions for improvements l_'!l Objections and ditliculties '-() Need for further investigations ol Results of experience with milkintr machines as reported by dairymen .'>!' Addendum ''>- II. BACTERIOLOGICAL STI'IdLS <>K A MILKING MACHINE. Production of sanitary milk ''>''> Experiments designed to test the sanitary character of machine-drawn milk.. :14 Experiments at Farm No. 1 .'14 Method of experiment. -'!4 First treatment of the milking machine- l!ii Second treat ment of the machines :>7 Third treatment of the machines 40 Eourth treatment of the machines 41 Fifth treatment of the machines 41 Sixth treatment of the machines . 44 Keeping qualities of the milk 44 Summary of experiments at Farm No. 1 . _ .. . 4"> 6 CONTENTS. Experiments to tost, the sanitary character of machine-drawn milk Cont'd. Page. Experiments at Farm No. 2 46 Method of experiment 46 First treatment of the machines 47 Second treatment of the machines 48 Third treatment of the machines 49 Fourth treatment of the machines 50 Fifth treatment of the machines 52 Sixth treatment of the machines 52 Keeping qualities of the milk 54 Summary ( if results of bacteriological investigations 54 ILLUSTRATIONS. Page. PI.ATK I. Kiy. 1. A foot-power milker with attachments. Fir. 1. Milking machine for use with either hand or power. Fir. 2. Same machine in operation 12 4. Fig. 1. Milking machine used in experiments. Fi*r. 2. The same machine in operation 12 Fi<;. 1. Bacteria in atmosphere of barn at farm No. 1 .'!."> 2. Bacteria in machine-drawn milk in experiment Xo. :!7 3. Bacteria in machine-drawn milk in experiment No. 101 4. Bacteria in milk drawn liy steam-sterilized machine in experiment Xo. 101 A ., -12 5. Bacteria in machine-drawn milk in experiment No. 10,'! J;i 6. Bacteria in atmosphere of Uirn at farm No. 2 4H THE MILKING MACHINE AS A FACTOR IN DAIRYING. .PRACTICAL STUDIES OF A MILKING MACHINE. By ('. B. .LANK, B. S. Assistant Chief, Dairy I)iris!on, Bureau of Animal Industry. INTRODUCTION. For more than a quarter of a century machinery has been success- fully used in separating the cream from the milk and churning it into butter, but a machine for milking the cows has been more difficult to supply. It has long been realized that a successful and practical cow milker would mean a profitable revolution of the dairy industry, as it would render the work of milking much easier and reduce the necessity for hired help, thus making the dairyman more independent. Efforts have been made by scores of inventors for more than half a centuiy to construct a machine that would milk cows in a satisfactory manner and without injury. The German writer Martiny states that ^ dif- ferent milking machines known to him had been patented in different countries or mentioned in the dairy literature between the years 1S77 and 1898. The annual reports of the United States Commissioner of Patents show that during the period of 84 years from 1.S72 to I'.Hjf), inclusive, 127 patents were taken out in this country alone for milking machines or separate parts of them. A number of machines have been success- ful in extracting the milk from the cow by either pressure or suction, or by the two combined, but have fallen short of being practical in some vital point. Naturally, inventors have attempted to imitate the wa} T in which the calf sucks its dam. The difficulty has been to reproduce the peculiar influence which the sucking calf has upon the cow and to devi.se a machine which will not irritate the animal and which will do its work without injury. Another difficulty in devising a cow milker has been to construct it so that it could be adjusted to all cow r s. Individual animals vary greatly in the si/e and conformation of their udders, and even the same cow varies somewhat in the si/e and shape of her udder and teats during the different stages of her 11522 Xo. ( J2 07 2 9 10 THE MILKING MACHINE AS A FACTOR IN DAIRYING. lactation period. Cows also vary greatly in disposition and temper- ament. A successful cow milker, therefore, must meet all these different conditions. Since milking must necessarily he an artificial process, it has been thought for some time that animals would become accustomed to being milked by machinery just the same as the}' become accustomed to hand milking, provided a milking machine could be perfected that would be comfortable to the animal when in operation. A heifer, for example, coming into milk the first time would take as readily to one artificial method as to another, other things being equal. While no milking machine yet invented has shown its practical value in a way that has led to its general use, recent improvements in machines of this type have resulted in greater simplicity of construction and effectiveness in operation, and consequently they are in practical use in a limited number of the larger dairies. Indeed, the prospect for the general introduction of milking machines appears to be so favor- able that it was thought advisable by the Secretary of Agriculture to authorize an investigation of the fundamental problems involved in the use of such machines. These fundamental problems may be stated as follows: (1) The practicability of substituting machine for hand milking in the actual operations of dairying: ('2) the effects of machine milking on the quantity and composition of the milk yielded by the cows; (3) the effects of machine milking on the cleanliness, sanitary character, and keeping qualities of the milk. In making such an investigation it was, of course, necessary to select some machine for use. The machine selected is OIK- which was found to be in actual use in a number of dairies, and one which appeared to offer adequate means for conducting the proposed inves- tigation. Its selection was not intended as in anv sense a recom- o mendation of this particular machine to the favor of dairymen. It is believed, however, that, in so far as the investigation has demonstrated the merits of this machine, it will benefit all inventors and manufac- turers of successful milking machines. The authors fully appreciate the fact that these investigations have been too limited to justify any .-weeping deductions or positive con- clusions. But in view of the probable general introduction of such machinery in the near future, it is believed the results of the investi- gations are of sufficient value to justify their publication. SOME MILKING MACHINES IN USE. As a complete account is hereinafter given of the machine used in the investigation, a brief description will suHice for the other machines presented here, none of which were used in this investigation, and in regard to the efficiency of which no opinion can consequently be exprest. SOME MILKING MACHINES. 11 A FOOT-POWER MILKER. This machine (pi. 1) is designed for use in small herds and has no sta- tionary fixtures. It consists of a suction pump worked by foot power, 2 pieces of rubber hose, and S suction cups to be attached to the teats of the 2 cows, which can be milked at the same time. The milk passes thru the cylinder, and also thru the valve in the pump piston itself. The operator sits between the 2 cows and works the pump with his feet. On opening- the spigot the suction rapidly draws the cups over the teats and the milk begins to flow into the milk pail, which is hung on the spout of the pump. The teat cups are hollow and conical. Nearly an inch from the largo end the cup is almost closed by a soft rubber diaphragm; this disk, being elastic, fits air-tight around the different-sized teats. The teats rill the conical cup except at the small end where suction is applied. The cup is made of three pieces of smooth hard rubber. To the end of the cup is attached a piece of glass tubing thru which the milk may be seen, and this is again connected with a small rubber tube. T$y means of a spigot in the tube the suction may be cut off when the teat is empty. The milk is conveyed from the spigot to the head where the milk from all four teats unites and passes into the large hose which carries it to the pail. This machine has been in operation since 1892. A POWER MILKER. The accompanying illustration (pi. 2) shows a cow milker which has recently been put upon the market. It consists of an ordinary" milk pail made of block tin and holding about 15 quarts. On top of this pail is a tight-fitting lid of aluminum. On this lid is mounted a pump or pulsator which works automatically and causes the intermit- tent action of the machine. Connections are made by means of rubber tubing to the exhaust and air-pressure pipes, which are laid thru the stable with convenient branches between the cows. Two rubber tubes, each about 3 feet long, are also connected with convenient nozzles on the lid, and on the other end of each are -4 cups which fit snugly over the cow's teats, 2 cows being milked into one pail. As the pulsator oscillates (at the rate of about 60 times a minute) the vacuum is alter- nately' turned on and off, the teat cups causing suction and release at each alternate stroke. The machinery for operating the pulsator consists of an exhaust pump and a compressor; the exhaust produces the suction and oper- ates the pulsator in one direction, while the compressor operates the pulsator in the opposite direction. 12 THE MILKING MACHINE AS A FACTOR IN DAIRYING. A MILKER DESIGNED FOR EITHER HAND OR POWER. The milking machine shown in Plate 3 consists of a. simple air pump, composed of two cylinders, each of which is independent of the other in its action. One cylinder milks one cow, and one the other. The valve chambers, supported at the ends of the rods, are for the purpose of keeping the milk from running back into the pump, and also to give the pump sufficient and continued suction for the space of about ten to fifteen seconds. When the pressure is off of one of these valve chambers the milk flows from it of its own gravity into the pail. Each cow can be milked separately, or both can be milked into one pail, as desired. Cows can be milked into either open or closed pails. The machine is operated by either hand or po\ver, the hand machine being convertible into a power machine by simply bolting an air device to it. In the operation of the power machine it is necessary to pipe the stables, a comprest air tank being required, which must be filled by some power running an air compressor. There are no pulsators or vacuum pumps in the construction of the machine. The teat cups are provided with a rubber sleeve. THE MACHINE USED IN THE INVESTIGATION. With this machine the milk is drawn by intermittent suction. The suction may be created by either a vacuum pump or a steam ejector. Connected with the vacuum pump is a vacuum reservoir and a pipe running the whole length of the cow stable, with a connection valve or vacuum cock between each pair of cows. A safety valve is connected to the reservoir to prevent the vacuum from running higher than is desired. The machine itself (pi. 4, fig. 1) consists cf a heavy tin pail, which is cone-shaped and holds about 55 pounds of milk. The cover of this pail is a disk, in which is a vacuum motor which produces the pulsa- tions in drawing the milk from the teats. The cover fits the pail tightly and excludes all air. To operate the machine it is placed between the pair of cows to be milked. A rubber tube connects the pail top or pulsator with the vacuum cock above the stanchions. On opening the cock the air is drawn from the pail and the motor immediately starts. The degree of pressure maintained is about one-half atmosphere, or 7^ pounds to the square inch. Leading from the pail cover or pulsator are two flexible tubes besides the one leading to the vacuum cock above the stanchions. At the end of each tube are 4 cups, which are fitted over the teats of the cow. The milk from the '2 cows is discharged into one pail (pi. -i. fig. 2). In operation the machine makes a low, click- ing sound, which is caused by the motor. The vacuum pulsations run from 50 -to T<> per minute and may be easily adjusted to the speed BUL. No. 92, B. A. I. PLATE 1 FIG. 1. A FOOT-POWER Cow MILKER WITH ATTACHMENTS. FIG. 2. THE SAME MACHINE IN OPERATION. ?UL. No. 92, B. A. I. PLATE 2. FIG. 1 . A POWER MILKER WITH ATTACHMENTS. FIG. 2. THE SAME MACHINE IN OPERATION. But. No. 92. B A !. PLATE 3. FIG. 1. MILKING MACHINE DESIGNED FOR USE WITH EITHER HAND OR POWER. FIG. 2. THE SAME MACHINE IN OPERATION. But. No. 92, B. A. I PLATE 4. FIG. 1. MILKING MACHINE USED IN EXPERIMENTS. FIG. 2. THE SAME MACHINE IN OPERATION. DIFFERENT KINDS OF POWER. 18 required. The milk in passing from the, cow to the pail goes thru a glass inspection tube, so that the operator may watch the How. When the milk ceases to flow the suction is turned off and the action of the machine stops. Four different sizes of teat cups are provided, so that different sizes of teats may be fitted. COST OF EQUIPMENT FOB MACHINE MILKING. At the present time the equipment required to milk a herd of 40 cows with the machines and the cost of the, same would be as follows: 1. An engine or some power with which to drive the machine. For milking up to 8 cows at a time, a 2-horsepower gasoline engine may be used, costing SI 05. 00 2. A vacuum pump, costing 75. 00 3. \ vacuum lank, like a tank that is used in connection with ranges or stoves in kitchens, costing 11. 00 4. The piping with valves, etc., necessary in barn, depending upon extent of plant, number of cows, etc., costing for a 42-cow dairy about 25. 00 5. Four milking machines, costing 300. 00 Total 516. 00 One machine milks 2 cows at a time, and it has been found practi- cable to allow one machine to every 10 or 12 cows when equipping the herd. In a general way it m&y be said that the entire cost of installing a plant for herds of different sizes would be about as follows: For a dairy of 30 cows, with 2 machines, milking 2 cows each or 4 cows at one time, cost per cow $13. 00 For a dairy of 40 cows, with 3 machines, milking (i cows at one time, cost per cow 12. 00 For a dairy of 60 cows, with 4 machines, milking 8 cows at one time, cost per cow 1 0. 00 For a dairy of 75 cows, with 5 machines, milking 10 cows at one time, cost per cow S. 50 For dairy of 100 cows, with 8 machines, milking 16 cows at one time, requir- ing about a 4-horsepower engine and a larger pump, cost per cow 10. 00 One good careful man or woman can operate -i machines milking 8 cows simultaneous^, and an additional hand can not only carry awjiy the milk, but assist in manipulating the cows' udders. The operating expense of the machines is comparatively small. DIFFERENT KINDS OF POWER WHICH MAY BE UTILIZED. The kind of power employed to operate cow milkers is not impor- tant provided it is uniform and can be depended upon. Dairymen well know that, in the case of hand milking, if they were to stop for a time when a cow was partially milked and then begin again and finish milking, the chances are that there would not only be THE MILKING MACHINE AS A FACTOR IN DAIRYING. a decrease in yield, but the milk would be of poorer quality. A sim- ilar effect is produced in the case of machine milking-. If the engine, or whatever power is employed to work the pumps, stops for an}' cause during the milking, a marked decrease in the yield of milk results. Gasoline engines, These are most commonly employed for power at the present time. Electric -motor*. Some farmers located near cities find electricity the most convenient power. This has worked successfully on two farms at least. In one case a trolley line passes near the barn and a wire is attached to the main trolley wire and connected with a 1-horse- power electric motor inside of the building. As electric roads are now being rapidly built thru country districts it is quite possible that this may prove a popular method of securing power to operate cow milkers. 8team power. Steam engines are employed on some farms, and they will be found to work satisfactorily in supplying power to operate the milking machines. Where steam is used on farms for other purposes it can be made to run the milkers with but little extra expense. EXPERIMENTS IN WHICH HAND AND MACHINE MILKING WERE COMPARED. Two experiments were conducted by the Daily Division in which tests were made to determine the time required to milk by hand and by machine. The yield of milk, its chemical composition, and other points that were considered of interest to dairymen, were also studied. EXPERIMENT NO. 1. From a herd of 13 cows, 8 were selected for this test, the others being nearly dry. The animals were Jerseys and Ilolsteins, all 5 years old or over. This herd had been milked with -the machines for over three years. The cows were divided into two lots of - each in such a way that eaclf lot gave practically the same amount of milk. The test con- tinued for thirty days and was divided into three periods of ten days each. At the beginning of the first period. Lot 1 was milked by hand and Lot II by machine. At the end of each period of. ten days the methods of milking the two lots of cows were reversed so that, the results from milking 1 by the two methods could be compared. The milking was all performed by one man. HAND AND MACHINE MILKING COMPARED. 15 TABLE 1. Machine milking: Time required to milk, and yield of milk and strippings. The cows and date. Morning. Evening. Total for day. Time required. Yield of milk. Time required. Yield of milk. Time required. Yield of milk. j! Strippings. 1 H Machine milk. s. 1.50 .80 aS.10 .50 .50 .50 .60 . 40 .40 .90 2 Machine milk. Strippings. Total yield. LOT II, 4 COWS. July 21... Min. 14.00 14.00 14.00 13. 50 14.50 13.00 12.50 13.00 13.00 12.00 Lbs. 30.50 36.50 31.50 36.50 35.00 36.50 34.00 30.50 38.00 37.50 I.b. 1.25 .50 .75 .50 .50 . 25 ft 5. 25 .75 .50 Lbs. 31.75 37.25 32.00 37.25 35.50 37.00 34.25 35.75 38.75 38.00 Min. 13.00 12.00 13.00 15.00 11.50 12.50 12.00 14.00 13. 50 12.00 Lbs. 25. 00 34.75 28.00 36.50 35.00 34.50 32.00 34.80 32.00 29.25 Lbs. 26.50 35.55 36.10 37.00 35.50 35.00 32.60 35. 20 32. 40 30.15 Min. 27.00 26.00 27.00 28.50 26.00 25.50 24.50 27.00 26.50 24.00 1*8. 55.50 71.25 69.50 73.00 70.00 71.00 66.00 65.30 70.00 66. 75 Lbs. 2.75 1.55 8.60 1.25 1.00 1.00 .85 5. 65 1.15 1.40 Lbs. 58.25 72.80 68.10 74.25 71.00 72.00 66.85 70.95 71.15 68.15 Julv 22 Julv 23 July 24 July 25 Julv 26 Julv 27.. Julv 28 Julv 29 Julv 30. Total Daily average LOT I, 4 COWS. Julv 31 133.50 346.50 13.35; 34.65 11.00 1.10 357. 50 35. 75 128. 50 12. 85 321.80 32.18 14. 20 1.42 336.00262.00 668.30 33.60 26.20 66.83 25. 20 693. 50 2. 52 69. 35 13. 00 30. 00 13.50 34.50 13.00 34.00 12. 50 36. 00 12. 00 32. 00 13.00 34.50 12. 50 32. 50 13.00 33.00 12. 50 33. 50 13.00 34.25 .75 .75 .50 .50 .75 .75 .75 .50 .50 .50 30.75 12.50 27.30 35.25 14.00 27.30 34.50 13.00, 27.00 36.50 13.00 24.00 32.75 13.00 24. ,50 35.25 15.00 26.25 33.25. 14.00! 25.50 33.50 14.00 ; 27.25 34.00 15. 50i 27.75 34.75; 13.00! 34.00 1.80 .50 .50 1.00 i!oo .30 . 75 . 75 .40 29.10 27. 80 27.50 25. 00 25. 25 27. 25 25. 80 28.00 28. 50 34.40 25. 50 27.50 26.00 25.50 25. 00 28. 00 26. 50 27.00 28.00 26.00 57.30 61.80 61.00 60.00 56.50 60.75 58.00 60. 25 61.25 68. 25 2. 55 1.25 1.00 1.50 1.50 1.75 1.05 1.25 1. 25 .90 59.85 63.05 62.00 61.50 58.00 62. 50 59. 05 61.50 62. 50 69. 15 August 1 August '' August 3 August 4 August 5 August 6 August 7 Augusts August 9 Total 128.00 334.25 12. 80: 33. 42 6.25 .62 340. 50 137. 00 270. 85 34.05 13.70, 27.08 7. 75 27S. 60 265. 00 .77 27.86, 26.50 605. 10 60. 51 14.00 1.40 619. 10 61.91 Daily average LOT II, 4 COWS. August 10 11.00 12.00 13.50 12.50 13.00 14.00 13.00 12.50 13.50 14.00 36.00 36.00 33.00 34.00 40.00 39.50 35.50 34. 50 33.00 40.00 .50 .25 .50 .25 !Eo .25 . 25 .50 36.50 11.25 30.10 36.25 12.00 32.00 33.50 15. 00 ''27. 75 34.25 13. 00 ''31. 00 40.25 16.00 26.00 39.75^ 16.50 33.50 36.00 13.50; 31.00 34.75 14.00 36.50 33.25 14.50 40.00 40. 50 16. 00 e37. 50 1.00 31.10 .25 32.25 5.25 33.00 3.75 34.75 1.50 27.50 .25 33.75 .70 31.70 .25 36.75 .50 40.50 5. 75 43. 25 22. 25 24.00 28. 50 25. 50 29. 00 30. 50 26. SO 26. .50 28. 00 30.00 66.10 68.00 60. 75 65.00 66.00 73.00 66.50 71.00 73.00 77. .50 1.50 .50 5. 75 4.00 1.75 .50 1.20 .50 . 75 6. 25 67.60 68 50 66.50 69.00 67.75 73.50 67.70 71. 50 73. 75 83. 75 August 11 August 12 August 13 August 1 4 August 15 August 16 August 17 August IS . August 19 Total Daily average Grand total .. General average . .. 129.00 361.50 12.90 36.15 3.50 .35 365.00 141.75325.35 36.50 14.17 32.53 19.20344.55 1.92 34.45 270. 75 686. 85 22. 70 709. 50 27. 07 tis. 6,s 2. 27 70. 95 390.501,042.25 13.02 34.71 20. 75 .69 1,063.00407.25918.00 35.43 13.57 30.60 41.15959.15 1.37 31.97 797. 75 1, 960. 25 61. 90 2. 022. 10 26.59 65.34 2.06 67.40 a One oi &Onec( (Black (I Black e Black lilk (7.5 pounds) on account of stranger being in barn, lilk (5 pounds) on account of stranger being in barn. milk and gave 4.75 pounds by hand. milk and gave 3 pounds by hand (stranger in barn). milk and gave 5 pounds by hand. THE MILKING MACHINE AS A FACTOR IN DAIRYING. TAKLE 2. Hand milk'tiiy: Time required l<> iitilk, and i/ield of milk and strappings. The cows nnd date. Morning. Evening. Total for day. c Yield of milk. Time required. Yield of milk. 5 Yield of milk. '= ? I ~ | tb '. 'C y. c '_ -5 7 "3 Stripping*. ~ LOT 1. 4 COWS. lv '! V/ 7./i.-. /./is / /IS Win //IS Us /6s ttis. 3.300 2. 500 2.700 2.500 2. .500 2. .500 2.250 2.000 2.600 3.650 /As. 66. 500 67. 700 64.900 67.500 67.25"' 72.500 66. 250 70.000 71.400 66.150 21.00 31 00 J 50 32.50 37. 50 35 00 20.00 16.00 17 00 32. 20 29. 20 8 ''0 1.80 1 . 00 1 70 34.00 30. 20 " 90 41.000 63.20 38. 000 65. 20 3. 500 62. 20 37. 000 65. 00 45. 000 (',4. 75 36. .500 70. 00 37. 500 64. 00 41.2.50 68.00 38. 500 68. 80 37. 000 62. 50 . Iv" 1 ' 22.00 36.0H 1.50 21.50 34 00 1 00 1 v >:? . 1 v 2 1 21.00 32.00 1.25 24.50 35.00 1.25 19.50 35.50 1.00 18.59 32.00 1.25 24. (X) 35.00 1.00 20.00 35.00 1.50 21 (Hi 3" 50 1 75 33. 25 36.25 36.50 33. 25 36. 00 36. 5( 34 '-"5 16.00 20.51 17. 00 19. CK 17.25 18. 50 16 00 3 !. 00 29. 75 31.51 32. 00 33. 00 33. 80 30 00 1.25 1 . 25 1 . 50 1. IX 1.00 1. H 1 90 34.25 31.00 36. 00 33.00 34. 01 34.90 31 90 . Iy25 . Iy26 . lv "7 ,ll lv 29 Ji lv 30 Total 213.00338. 00 13. CO 21.30 33.80 1.30 351.00177.25 35.10 17.72 315.65 31.56 13.50329.15 1.35 32.91 390. 250 653. 65 39. 025 65. 36 26. 500 2. 650 680. 150 68. 015 Daily n \vrasre.. LOT II. 4 ( HWS 26.00 S7.00 .75 25. .50 31.00 .75 21.50 34.00 .75 23. 00 26. 00 a 7. 50 23.50 31.00 .75 21.00 36.00 . 75 24.00 31.50 22.00 35.00 23.00 36. 50 21.00 36.00 47. 000 45. 500 40. 500 44.000 43. 500 43. 500 43. 000 45. 000 44.. 500 43.1100 63. 850 6^.500 65. 900 66. 800 7u. 000 63. 500 67. 200 71.950 70. 400 Total Daily average 133. 50334.00 13.2" 3!7.2.>20i;. On:;21.65 31.75. 19.00 24.00 29.00 20.00 25.25 31.25 16.00 2v 50 33.25 H.i. UO 26.25 32.50 l;l.0:i 29.00 31.1 16.00 'JS.-J 31.75 IS. 00 29. 31.75 17.00 32.0 33.25 IV 00 31.5 43.000 41.000 37.000 10.000 39.000 37.0011 39.000 37. ( 00 oiio 1 . 550 1.600 2.500 1.250 1 . 750 2. 500 2. 000 2.000 Total.. ... 210.00307.00 186. 45 20.150 606.600 Grand ti itnl . i;56. 50 979. Oi 33.76 18.71 30.66 1.15 31.81 HAND AND MACHINE MILKING COMPARED. 17 TIME KEQUIRED FOR HAND AND MACHINE MILKING COMPARED. Naturally one of the first questions asked when a dairyman is con- sidering the installation of milking machines is: How much time will be saved by their use? In the experiment outlined above one man performed the milking-, 1 cow milker being used in case of the lots milked by machinery. The machine was operated by a 1-horsepower electric motor. By referring to Tables 1 and 2 the reader can readily compare from da} 7 to day the time required to milk by the two methods. A glance at the general averages for thirty days shows that the average time required for one man to milk 4 cows with the machine was 13.02 minutes in the morning and 13.57 minutes in the evening, or a total of 26.50 minutes for the day. These figures include the time used in putting the machine in place and adjusting the teat cups,, about one-fourth minute per cow being required to adjust them properl} T . In considering the time, the amount of milk secured should also I e considered. Other things being equal, cows producing a large amount of milk require the most time to perform the milking. In case of the 4: cows milked by hand it will be noted that it took an average of 21.88 minutes to milk them in the morning and 18.71 minutes in the evening, or a total of 40.50 minutes for the day. There was therefore a daily saving of 3.5 minutes per cow. or 14 minutes on 4 cows, thru the use of the machines. It should be noted, however, that the time saved by the employment of machines was not the result of greater speed in milking, but in the operator's ability to milk 2 cows at once. Indeed, one man can look after 5 machines milking 10 cows at once, thus greatly increasing this saving of time. (See experiment No. 2.) Speed of the machine. As stated in the description, the pulsator can be adjusted so that the action will be fast or slow; 50 to (>0 pulsa- tions per minute is the rate usually recommended. The more rapid the pulsations the faster the machine will milk, up to a certain limit. The writer saw one cow, giving a good How. milked absolutely clean with a machine in 2^ minutes, the number of pulsations being' 150 per minute. It is believed, however, that such rapid milking for any length of time has a bad influence upon the cow and after a time she might object to the machine and refuse to give down her milk. Cows vary greatly individually, and it is the best plan to adjust the speed of the machine as close I} T as possible to the requirements of each cow. Cows with short teats can he milked with the machine set at greater speed than cows with large, long teats. The ordinary type of lloL'2 No. i:> U7 o 18 THE MILKING MACHINE AS A FACTOR IN DAIRYING. Ayrshire cow, for example, can probably be milked by more rapid pul- sations than the Holstein. Those acquainted with milking- these two types of cows by hand know this to be true, and that in milking some cows the milk is ready to be drawn as fast as the milker can manipu- late the teats. While the machines were in operation the attendants massaged the udders of the cows and watched to see that they were milking freelv. Care was taken to treat the animals as nearly as possible the same at each milking, so they would become accustomed to the machines. YIELD OF MILK FROM HANI) AND MACHINE MILKING COMPARED. The yield of milk is perhaps the most important matter to the dairy- man. Any method of milking that has a tendency to decrease the flow to am- appreciable extent can hardly be considered practicable. This point was studied for a period of thirty days in this experiment with the milking machine. While a much longer period is necessary to settle this question, the results secured indicate at least what may be expected when the machines are properly handled. In this test the cows were carefully handled, care being taken to adjust the teat cups to suit the individuality of each cow, also to use cups of the same size on each cow every time. As already stated, two lots of cows were selected that yielded prac- tically the same amount of milk. Keferring to Tables 1 and '"1 it will be noted that the total yield of milk for 4 cows during thirty days was 1.898.75 pounds from hand milking" and 1,960.^5 pounds from machine milking/' not including strippings a difference of t!1.5 pounds, or 3.24 per cent, in favor of the machine. A study of the yields of the different lots of cows ror the different periods shows that Lot I. which started with hand milking, gradually decreased in milk flow when changed to the machines and also continued to decrease when changed again to hand milking. The yields of Lot II. which began with machine milking, show that these cows decreased when changed to hand milking and materially increased in yield when changed back again to machine milking. "One cow held up part of her milk from machine milk- ing, a difference of 3.9 pounds also in favor of the machine. This further comparison will serve to strengthen the conclusion already given that when the machines are properly handled and carefully adjusted to suit the needs of individual cows the yield of milk com- pares favorably with that of hand milking. 20 TTTK MILKING MACHINE AS A FACTOR IN DAIRYING. THOKONKHH OF HANI) AND MACHINE MILKING COMPARED. A machine that does not milk cows clean, or at least as clean as the average farm hand does, is of but little service to dairymen. This point was tested as thoroly as possible in the experiment just described. The man who milked the cows by hand in this experiment was instructed to milk the cows as normally as possible and not to go to extremes in either direction. It is believed that a fair trial was made in this respect. Keferring to Table 1 it will be observed that the amount of strip- pings was fairly uniform from day to day in case of both hand and machine milking. A comparison of the amount of strippings from each lot of cows for the three 10-day periods is shown in the following tabulation: Comparison of amount of strippings in hand and machine milkintj. Hand milking: Pounds. Lot I, first period 2<>. 50 Lot I I, second period 21 . 70 Lot I, third period 20. 1 5 Total.. . 68.85 Machine milking: Lot II, first period 25. 20 Lot I, second period 14. 00 Lot II, third period 22. 70 Total 61 . 90 The total strippings from hand milking for the -i cows for thirty days is shown to be 68.35 pounds, and from machine milking <>L.i) pounds, or 6.15 pounds less for the machine. The average strippings per cow for each milking was -L55 ounces by hand and 4.12 ounces by machine. The composition of the milk was not determined in this experiment. EXPERIMENT NO. 2. This experiment was conducted with 20 cows selected from a herd of 65. All kinds of cows were selected for the test, including hard and easy milkers, heifers, and mature animals, and fresh cows as well as those advanced in lactation; also including cows of nervous temper- ament which it was known did not take kindly to the machine. This vvas done in order that a thoro study might be made. The 20 cows were divided into two lots of 10 each, which we will designate as Lots land II. HAND AND MACHINE MILKING COMPARED. 21 Lot I was milked by hand and Lot II by machine for a period of 10 days; the methods of milking were then reversed and Lot I was milked by machine and Lot II by hand, 2 days being allowed between the periods to make the change. Five machines were used to milk the 10 cows. These were handled by one man. One man also milked the 10 cows by hand the greater part of the time. Whenever more than one man was employed the results were put on the basis of one man; that is, if two men milked the 10 cows in 40 minutes this was considered equivalent to one man milking 80 minutes. This exper- iment differed from the one previously described in that more cows were included and less attempt was made to adjust the teat cups to the different cows or to use the same machine on the same pair of cows every time, this matter being left largely to the dairyman in charge. These points will be considered in studying the results. 22 THE MILKING MACHINE AS A FACTOR IN DAIRYING. r -i- -f. m -.-. -.'-. :- cc :c :? 9iC ... . o 8S8SSSSSSSS O 1^ t^ X X ri ^ -T GC tC *) co c v-t T CNI o-t re -r n 000 O ; X X X X X X X X 'S. S. HAND AND MACHINE MILKING COMPARED. x v. x; x x x oc x -x o i': ic ic o i" ic o 3 is o ri .c n o co -i ic CO CO CO CO CO M' CC CO CO CO 00=0200000 -.'. o ic x -r x ss o : CT. O - O 5. ~. O X SiC 1C c i - cr. co ci co co co co tc t "7 I ~ CO 1C '-w CC ' I * 1C -T x' x' CC 5C X' V. 30 CC X X cccococococococccoco o g o g 5 o o o o o ogggggogoo g g g o o o 2 o o g o-iooooooo; 0000000=0: Soo?,?oS,cSS '5 3 o o S x' x 7. ~. l ~. x -co -5 S '/ XXX X X 00 X X 'X X ,9000505500 55 |2 o -r 7JO I Xoi - - 7 > c 5 24 THE MILKING MAOHTNK AS A FACTOR IN DAIRYING. TIME KEQUIRED FOR HAND AND MACHINE MILKING COMPARED. The accompanying table shows the time required to milk the cows by the two methods during the different periods. In this experiment one man handled 5 machines with little difficulty. The man who milked the cows by hand was unusually thoro and took somewhat more timo to do the work than the average milker. It will be noted that the average time required for one man to milk the 10 cows with the machines for 20 days was 19.4 minutes in the morning and 17.67 minutes in the evening, or a total of 37.07 minutes for the day. The time stated includes the time required for putting the machines in place, adjusting the teat cups, and milking; the aver- age time per cow being 1.04 minutes in the morning and 1.76 minutes in the evening, or a total of 3.7 minutes for the day. In the case of the 10 cows milked by hand it will be noted that it required for the 20 days an average of 81 minutes in the morning and 73.9 minutes in the evening, or a total for the day of 154.9. The average time required per cow was therefore 8.1 minutes in the morn- ing and 7.39 minutes in the evening, or a total of 15.49 minutes for the day. On the basis of these results the daily saving per cow thru the use of the machines amounted to 11.79 minutes, or 117.!) minutes for the 10 cows. Carrying the comparison still further, the saving for 60 cows (the number in this herd) would amount to 11.7 hours per day if one man performed all of the work, which of course would not be possible for a herd of this size, altho the writer has known one man to milk 60 cows with 6 machines on more than one occasion, the time required being about 2 hours. If, however, we include the time of the man who removed the milk and assisted in manipulating the cow's udders the saving of time is reduced to one-half, or 58.45 minutes per day for the 10 cows. These figures furnish sufficient proof for the statement that the machines are t; time savers.' 7 YIELD OF MILK FROM HANI) AND MACHINE MILKING COMPARED. As previously stated, but little attention was given to properly adjusting the machines by the attendants in this herd. Further than this, it was known that 1 or 2 of the cows selected did not take kindly to the machine, but it was desired to have the cows in the test represent the average of the herd. While a longer period than 20 days would have been desirable, the results indicate, at least, what may be expected under the conditions which prevailed during this test. Referring to Table 3, it will be observed that the total yield of milk for 10 cows during the 20 days, was 4,371 pounds from hand milking and 4.062.5 pounds from machine milking, not including strippings a difference of 308.5 pounds, or 7.59 per cent, in favor of hand milking. HAND AND MACHINE MILKING COMPARED. 25 This result is not surprising when we consider the careless manner in which the machines were adjusted to the animals, and that this fre- quently resulted in the animals holding up their milk. Further, the fact should be noted that the hand milker in this instance was unusu- ally careful, taking an average of 7.75 minutes to milk a cow at each milking. The results tend to show that where milking machines arc used carelessly they are a disadvantage to the dairyman from the standpoint of yield. The same holds true of other machinery on the farm; the more complex it is the more care and skill is required to secure the best results; but with skill and care the more machinery the better, up to a certain limit. This is brought out in experiment No. 1, where the milking machine held its own or showed an advantage at every point. THORONESS OF HANI) AND MACHINE MILKINO COMPARED. As previously stated, the man who did the milking in this experi- ment was an unusually thoro milker and consequently took more time for milking than the average milker. While possibly it would have been better to have employed an average milker in this experiment in order to make a fair comparison, the question as to whether the milk- ing was thoro by both methods can be made clear. In a few instances 1 or 2 cows refused to give clown part of their milk (probably owing to the teat cups not being of the proper size). This of course increased the amount classed as strippings. A comparison of the amount of stripping^ (including the amount held up by the machine-milked cows, as explained above) from each lot of cows for the 10-day periods is as follows: Hand milking: Founds. Lot I , first period 30. 50 Lot II, second period 37. 50 Total . . . 08. 00 Machine milking: Lot II. first period 47.00 Lot I, second period 3S. 20 Total So. i'(> The total strippings from the hand and machine milking for the 1<> cows during '20 days is thus shown to be OS pounds and So. 2 pounds. respectively. On this basis the average strippings per cow at each milking amounted to '2.7 ounces by hand and 3.4 ounces by machine. In either case the results show unusually clean milking. 11522 No. i2 ii7 4 '2< THE MILKING MACHINE AS A FACTOR IN DAIRYING. QUALITY OK THE MIJ.K. Percentage of butter Jut in milk. A sample of the mixt milk was taken at eveiy milking- in experiment No. 2 and tested for percentage of fat by the Babcock method. The results of the daily tests are shown in Table 3 and the average for the different periods has been brought together for ready comparison in the following tabulation: Percentage of butter /at In milk pounds of butter, or about 13 per cent. This appears to be quite an unfavorable showing for the machine, but further experiments are necessary to determine the effect of machine milking on the composition of milk, as it is always unsafe to base general con- clusions on the results of a single experiment. J^/'C'-nt/ii//' of Ndlirfx not fiii." The percentage of solids not fat was determined by means of the lactometer. Tests were made from samples taken both morning and evening. The detailed results are given in Table 3. but in order to make a more ready comparison only the aver- ages are presented here. "These tests were made bv Prof. W. A. Stocking. EFFECTS OF MACHINES UPON COWS. 27 Percentage of solids not fat in milk drawn by hand and by machine. Hand milking:: Percent. Lot I, first period ( 10 days) 8. 58 Lot II, second period (10 days) 8. 46 Average 8. 52 Machine milking: Lot II, ri rst period ( 10 days ) 8. 55 Lot I, second period ( 10 days ) 8. 59 Average 8. 57 The tinal averages shown above for the .solids not fat are very close, being 8.52 and 8. 57, respectively, for the hand and machine milk. While further study should be made on this point, the figures secured indicate that there is practically no difference in the amount of solids not fat between machine and hand drawn milk. GENERAL, CONSIDERATIONS. EFFECTS OF MILKING MACHINES UPON THE COWS. First time machine is used. It is of interest to note how the milk- ing machine affects a herd of cows the first time it is used. The writer was present in a barn of about -io cows on one occasion the first time the machines were put in operation. Some of the animals were a little restless at first, owing to the sight of the machines and the clicking of the pulsators, but soon they became quiet and reconciled to their action. One feature which is perhaps a little surprising is that heifers took to the machines as readily as the older cows. Only one cow in the herd in question made any disturbance at all while the machines were being attached, and this was due principally to attaching the machine on tin 1 opposite side from that on which the cow had been accustomed to be milked by hand. This cow. however, soon became quiet. The majority of the cows appeared to like the machines, and stood quietly chewing their cuds without manifesting any discomfort. A careful examination was made of the cows' teats and udders in several dairies where the machines had been in operation for several months (in one case over three years), and no ill effects were discovered. Nervous <'<>/r*. On two or three occasions it was observed that when strangers came into the barn during milking time a cow would appear frightened and refuse to give down all of her milk. This occurred with cows being milked either by hand or by machine. When the machines are properly adjusted, cows of a nervous disposition do not seem to resent the method. I\H-l\iiHj ro//'\. The writer, after visiting from time to rim* 1 several herds where the machines were in operation and observing the ma- chines working continuously in one lar<_n> herd fora month, failed t<> 28 THE MILKING MACHINE AS A FACTOR IN DAIRYING. find any cows that could not be milked because of the "kicking" habit. Reports from dairymen who have had experience with the machines confirm this statement. It is therefore believed that the machines give less trouble with such animals than the hand method. Hard in ilker*. The hard milker and the cow with small teats are milked much more easily and quickly by machine than by hand, and with the installation of milking machines there will be less reason for disposing of such cows. With the hard milker it is simply a question of keeping the machine at work a little longer, and with the small- teated cow care must be taken to have the teat cups of the proper size, and the pulsations may also be a little more rapid. JIe'tf<-rx. The results already secured indicate that the milking machine is particularly well adapted to heifers. Since milking i.s an artificial process, heifers that have never been milked by hand, as a rule, become much more quickly reconciled to the machine than older animals which have been milked for years by hand. The latter often have their udders more or less distorted and drawn out of shape by the hand method and do not as readily adapt themselves to the machine method. Coo.'* tJit refiixt to l>e milked v always take the >ame places in the barn and GENERAL CONSIDERATIONS. 29 using teat cups of the same si/e at each milking. Cows will then become accustomed to the cups and will milk clean. PRACTICABILITY OF USING MACHINES FOR LARGE A\D SMALL IIEKDS. ^Naturally the largo dairyman will be the first to adopt the cow milker for the reason that his equipment will cost him less per cow than the small dairyman. Again, the large dairvman has more at stake and has to depend entirely upon the hired men to do the work. If they fail him the work falls upon himself or perhaps upon a very limited number of helpers. With the installation of the milking machine the large dairyman is much more independent, and if necessary could milk a herd of 5<> cows without assistance. This would be next to impossi- ble without it. However, there seems to be no good reason why a dairyman with a herd of even lo or 12 cows could not use a machine with profit. The power required could be secured at small cost, and the time saved could be used to advantage in working the team longer on the farm or in other ways. HOW THE GENERAL INTRODUCTION OF THE MILKING MACHINE W T OULD AFFECT THE DAIRY INDUSTRY. The scarcity of milkers and the unreliability of many of them has had a tendency to keep many men from going into dairy farming. Some dairymen who have been in the business have been obliged to give it up for this reason. Great interest therefore centers around the milking machine, especially where the above difficult}" exists. With the introduction of the milking machine only about one-half the labor will be required to milk the cows, and it is believed that the labor employed will be of a higher class than heretofore and will also command higher wages. It is believed also that the advent of the milking machine will have a tendency among farmers who now have small dairies to enlarge their plants and to make dairying their chief business. The trouble has been in the past that too many farmers have made dairying secondary to other work, and when anything had to l>e neglected it was always the dairy. For this reason the profits from their dairies have boon small. Where the milking machines have been introduced they have influenced dairymen to clean up their burns and take more pride in their work. This naturally will result in the pro- duction of cleaner milk and perhaps in some cases in bettor prices. Any new apparatus which has a tendency to improve dairy conditions should be welcomed by the industry. SUGGESTIONS FOR IMPROVEMENTS. Improvements will doubtless be made in this milking machine from time to time. At present two cows are milked in the same can. thu- making it impossible to secure the weight of the milk from >ii,-u'le 30 THE MILKING MACHINE AS A FACTOR IN DAIRYING. cows. A great deal of importance is now being placed upon records of individual cows in order to determine whether they are giving a profit to their owner, and this is a movement in the right direction. If individual cans were provided for the cows, accurate records could )>e secured for each animal. The difficulty of making machines for individual cows is not insurmountable: in fact a few machines have already been built which keep the milk from the two cows separate. Another improvement that it is believed would add much to the practicability of the machine is a teat cup that could readily be adjusted to teats of any size or shape. At present cups of different sizes are used to meet the requirements of different animals. Some improve- ments in this direction are already in progress. OBJECTIONS AND DIFFICULTIES. As attention has been called to the advantages to be secured by the use of milking machines, it is proper to point out some of the objections and possible difficulties. Initial outlay. The considerable outlay in the beginning will prove a serious obstacle to dairymen of limited means; and, even with those who are financially able to make the investment, it will have a tendency to deter dairymen from the installation of machines until their practical utility has been fully demonstrated. Gardens or improper uxe. As already suggested, the machines may be improperly or carelessly used. The operator may fail to select and use teat cups which fit. etc. Life of the inachin'-. The machine or some of its parts may prove short-lived, thus causing expense and trouble. Troiil>lr<-nl'ir/,x. In the operation of any kind of ma- chinery there is always danger that some part will break down or get out of order. With most machinery this is not a very serious obstacle, -hire the work to be done can await repairs. But milking is work that can not be postponed. Attention has been called to the independ- ence of the dairyman who milks with machines as compared with the one who must depend on hired help to milk his cows by hand, inas- much as the latter may find himself short of help at any time. The situation, however, is re\ersed when the engine or some other vital part of tin 1 equipment breaks down or gets seriously out of order. If NEED FOR FURTHER INVESTIGATIONS. 31 this occurs at or during milking- time (as is likely), the dairyman wtro has installed machines, with 40 or more cows to milk, will find it very difficult, if not impossible, to bring in milkers enough to do the work by hand; and the difficulty will be aggravated if he loses time in unsuc- cessful attempts to repair the machinery. Cleaning and care of the inachin^. As this matter proper!}* be- longs in the second part of this bulletin, it need only be mentioned here as one of the difficulties which will demand the most serious attention of the dairyman who may attempt the use of milking machines. NEED FOR FURTHER INVESTIGATIONS. It is believed that the present investigations have yielded much valuable data, but they have been too limited in scope and time to justify final positive conclusions, even if the results had been uniform in their indications. The fact that they were not entirely so empha- sizes the need for further investigation. [ r ))Nf'ttl<-() minutes. In the case where '2 men handled 4 machines 27 cows were milked in -iO minutes. In the two instances where '2 men handled 5 machines they milked an average of 52 cows in (>8^- minutes. Where '2 men handled machines the time required was 1 minute per cow. Again where 3 men and bo} T s were just learning they milked 30 cows in 55 to 75 minutes. Some of the advantages of the machines reported were less help, less time required, and more and cleaner milk. One dairyman reported the cost to be a disadvantage, and another considered it a disadvantage to run the gasoline engine in winter. From 1 to -i cows in the different nerds were reported as refusing to give their milk with the machine. Some reported having this trouble at first but said that later it disappeared. Eight dairymen out of 11 did not think it necessary to strip the cows after using the machine, '2 thought it advantageous, and 1 simply stated that there was very little milk left after using the machines. Six dairymen stated that they found little difference in the amount of milk produced, whether the cows were milked by hand or machine; i thought the machines increased the How. and 1 stated that the effect of the machines on production was good. All of the dairymen reported machine milking to be superior to hand milking. ADDENDUM. Since the experiments described in this bulletin were conducted (August, 1905), the condition of the milking-machine industry has greatly changed. Certain improvements have been made. For ex- ample, the milk ports thru the pulsator have been enlarged; a tilter between the pail and the stanchion has been introduced, greatly reduc- ing the number of bacteria; and the surging of the milk in the tubes has been prevented. The sanitary features have also been improved. Over a thousand of the machines arc now reported to be in use. II. BACTERIOLOGICAL STUDIES OF A MILKING MACHINE. By W. A. STOCKING, Jr., M. S. A., BacteriologiM, Storrs Agricultural Experiment Station; Professor of Dairy Bacteriology, Connecticut Agricultural College. PRODUCTION OF SANITARY MILK. At the present time there is a greater demand for milk which has been produced and cared for under such sanitary conditions as to insure its reaching the consumer in a pure, wholesome condition than for any other dairy product. In order to supply this demand the milk must reach the consumer in as nearly as possible the condition in which it leaves the udder of the healthy cow. One of the great difficulties in the wa} T of supplying consumers with such a grade of milk lies in the dirt and the bacterial contamination which it receives before leaving the farm. As our knowledge of the laws of sanitation and the importance of pure foods becomes more widely disseminated among milk users this demand for a cleaner and more wholesome grade of milk will steadily increase. One of the greatest problems for the milk producer to solve is, therefore, that of producing such a grade of milk. A few dairymen are now producing a high grade of milk under such sanitary conditions as reduce the dirt and bacterial contamination to a minimum. For this purpose covered milk pails are commonly used, and great care is taken that the cows, the stables, the utensils, and the milkers shall be kept as clean as possible. All this extra care and labor is costly, and the milk thus produced demands a price considerably above the ordinary market price. This grade of milk tills a limited demand for those who can afford to pay the con- siderably increased price, but the problem of the milk supply for our cities will not be solved until the general consumer can be supplied with pure, clean milk at a reasonable price. While the exercise of this increased care and the use of the covered pail reduce the chance for external contamination very materially and greath T improve the quality of the milk, the ideal condition would lie to draw the milk directly from the udder into a closed receptacle with- out any chance for external contamination. This idea has stimulated in no small degree the inventors of the various styles of milking machines which have been developed during the last few years. 33 84 THE MILKING MAOHINP] Aft A FACTOR IN DAIRYING. While, it has been possible with some of these machines to draw the milk thru closed tubes directly from the udder into a closed recep- tacle, none of them have thus far proved satisfactory in all respects. If a machine could be devised which would be satisfactory in its effect upon the cow and upon the yield of milk, arid which can be cleaned with reasonable ease and at the same time all contact of the milk with the surroundings could be prevented, it would go far toward solving the problem of providing the public with clean, wholesome milk. EXPERIMENTS DESIGNED TO TEST THE SANITARY CHARACTER OF MACHINE-DRAWN MILK. In planning this experimental work the writer had three main objects in view: (1) To determine the germ content of machine-drawn milk in comparison with that drawn by hand; ('2) to test the efficiency of the machine in reducing the germ content to the minimum, and thus to determine its value in the production of "sanitary" milk; and (3) to determine the amount of care necessary to keep the machines in a sterile condition. Two farms were chosen for this work; one, a dairy where the sani- tary conditions were about the average existing in dairy barns, and the other representing a higher class of dairy barns in which sanitary milk might be produced. EXPERIMENTS AT FARM XO. 1. The first barn selected for this series of experiments is believed to represent about the average sanitaiy conditions of dairy barns in the principal dairy sections of the country. As may be seen by refer- ring to the illustration (pi. 4, tig. '2), the barn itself was in good condi- tion. The feeding alley, mangers, and drop were all of cement, while the stable floor on which the cows stood was of plank. The stable had been whitewashed and was fairl^v clean, but no special care was exer- cised each day in cleaning either the stable or cows nor in handling the milk. METHOD OF EXPERIMENT. In order to eliminate the difference due to the germ content of individual udders and give greater practical value to the work, two lots of 10 cows each were used in this series of tests. One of these lots was milked by machine and the other by hand. Samples from the mixt milk of each lot of 10 cows were taken as soon as the milking was completed and were carried to the laboratory. Owing to circum- stances it was impossible to plate samples at night. The evening samples were therefore placed on ice until the following morning. The morning samples were also placed on ice as soon as obtained and plated after they were thoroly chilled. It is of course possible that there may have been some slight increase in numbers in the samples BACTERIOLOGICAL STUDIES. 35 of evening's milk before they were plated. It is probable, however, that there was normally no appreciable increase but rather a decrease in total numbers, due to the natural dropping out of certain species in accordance with the so-called "germicidal property' 1 of milk. In either case the value of the results is not affected, since the hand- drawn and machine-drawn samples were treated alike in every case, and it is the comparison of these which is of value. In order to determine the numbers of bacteria existing in the milk, plate cultures were made in litmus sugar gelatin. In plating any sample of milk it is of course a problem to know just what dilution to use in order to obtain the proper number of colonies in the culture plate. In order to be sure of getting satisfactory results two or three differ- ent dilutions were used in plating the milk, duplicate plates being made from each dilution. In most ex- periments all the plates developed with satisfac- tory numbers and the aver- age of all was taken as rep- resenting the number of bacteria present in the milk, so that the figures given in this report repre- sent the averages from the four or six plates made by the two or three dilutions from the same sample of milk. As soon as the plate cultures were made they were placed in an incubator in which a constant temperature of TO F. was maintained, cultures were allowed to develop for live days, at the end time they were studied for the following points: 1. The total number of bacteria. '2. The number of acid-producing bacteria. '>. The number of liquefying or enzyme-producing bacteria. The total number of bacteria indicates the amount of the contami- nation the milk has received. The number of acid-producing organ- isms was determined separately from the others because of their importance in connection with the keeping properties of the milk. The group of liquefying organisms includes those species which gain access to the milk thru tilth and tend to produce putrefactive changes in it. It is this group especially which it is desirable to exclude from milk intended for human consumption, since it is believed that it farm No. 1. fur live the atmosphere Here the of which 36 THE MILKING MACHINE Aft A FACTOR IN DAIRYING. members of this group sire associated with certain digestive troubles, especially in children. It was believed that si study of this group might show interesting comparisons between hand-drawn and machine- drawn milk. The comparative data upon the keeping quality of the different samples of milk were obtained by taking subsamples as soon as the milk reached the laboratory, one of these subsamples being kept at a constant temperature of 70 J F. and the other placed in an ice chest where the temperature did not vary greatly from 50 F., or that which is commonly maintained in home refrigerators. FIRST TREATMENT OK THE MILKING MACHINES. As previously stated, one of the points which the writer wished to determine was the amount of care necessary for the proper cleansing of the machines after each milking. For this purpose the treatment which the machines received was varied from time to time during the period covered by the tests. The treatment which the machines received is used as a basis for grouping and tabulating the results, and the effect of the various methods used in washing the machines will be brought out in the succeeding tables. In the iirst place, it was desired to determine the efficiency of the method already in operation on the farm for washing the machines. This method was as follows: After the morning milking the machines were washt in water to which had been added some sal soda or other washing powder. They were then rinsed by pumping hot water thru them. After the night milking they were simply rinsed with cold water. The machines were not taken apart. The germ content of the milk drawn with the machines treated in this way, in comparison with milk drawn by hand, is shown in Table -i. TABLE 4. Comparison of results of hi bacteria ]>er culm E> Too numerous to count with the dilution used. EXPERIMENTS AT FARM NO. 1. 37 It will be noticed, in the column marked "Total bacteria," that the machine-drawn milk contained in every case decidedly larger numbers of bacteria than did the milk drawn by hand at the .same milking. The numbers obtained in the hand-drawn milk are about what might be expected from the ordinary method of hand milking in a barn of this o-rade, but the numbers in the machine-drawn milk are very much 0, the average in Table 5 was 327, -100 for the night milk- ing and 153,6<>0 for the morning milking. At the same time that this decided falling off in the numbers of bacteria in the machine-drawn milk occurred, the bacteria in the hand-drawn milk in the nisrht EXPERIMENTS AT FARM NO. 1. 39 samples, as shown in Table 5, was not materially smaller than in Table i, while in the morning milk the numbers were decidedly smaller. These differences are no greater than would be expected in any series of bacterial tests taken under similar circumstances. In the morning's milk, as shown in Table 5, the numbers of bacteria were also decidedly smaller in the machine-drawn milk. The most important fact to be noted here is the changed relation existing between the bacteria in the machine-drawn and hand-drawn milk. As shown in Table -i, before the machines were cleaned the milk drawn thru them contained many times more bacteria than did the hand-drawn milk, while after the cleaning, and with the brine treatment, the machine-drawn milk con- tained approximately only one-half as many bacteria as were contained in the milk drawn by hand. A study of the acid-form- ing organisms reveals the fact that it was in this group that the decrease in numbers took place. While in the machine- drawn milk, in Table 4, there was an average of over 90 per cent of acid- producing organisms, in Table 5 the percentage of these bacteria was 36.4 (night) and 52. 8 (morning). This decrease in the acid- forming bacteria in the ma- chine-drawn milk in this series of tests completely reversed the relation exist- ing between the bacteria found in the machine-drawn and hand-drawn milk, as shown in Table 4. In this series of tests it will be noticed that in almost every case the machine-drawn milk contained decidedly smaller total numbers of bacteria than did the corresponding hand- drawn milk. The same relation exists in the acid organisms, the machine-drawn milk containing both a "lower total number and a lower percentage of acid organisms than did the corresponding hand-drawn milk. The night's milk as shown in Table 5 contained an average of 36. -4 per cent of acid organisms for the machine-drawn milk as against 53.7 per cent for the hand-drawn milk, and in the morning's milk these percentages were 52.8 for the machine-drawn and 64.8 for the hand-drawn milk. .Essentially the same relation in regard to the liquefying organisms in the machine-drawn and hand-drawn milk is shown in Table 5 as was shown in Table 4. The average percentage 40 THE MILKING MACHINE AS A FACTOR IN DAIRYING. of liquefiers in the machine-drawn milk of the night samples was 8.5, while it was 11.4 in the hand-drawn milk. In the morning's milk, that drawn by machine contained an average percentage of 9.9 and the hand-drawn 12.fi of liquefiers. The principal value of these two tables lies in the fact that they show such a marked decrease in the bacteria found in the machine-drawn milk, this decrease being the result of the greater care used in the washing of the machine. THIRD TREATMENT OF THE MACHINES. In spite of the greatly reduced number of bacteria obtained in the machine-drawn milk, the writer believed that the machines were not being properly sterilized. To test this, cultures were made by shaking- sterile water in the rubber tubes after they had been washed as usual. The plate cultures made in this way showc d that the short tubes and the ends of the long ones contained only small numbers of bacteria, but that the central part of the three long rubber tubes was still filled with bacte- ria, which were not being killed or removed by the method used for cleaning the machines. A further test of this point was made in connec- tion with experiments 77 and 78 by milking two cows with an entirely new machine. The milk thus obtained showed a germ content of 17,<>12 bacteria per cubic centimeter. At the same time the milk drawn into the machine which was in regular use contained 223,750 bacteria. This great difference in numbers of bacteria found in the milk drawn into the old and the new machines, together with the fact that such large numbers were- found in the tubes used on the old machine, was considered definite proof that the daily care used in clean- ing the machines was not sufficient to prevent their becoming breeding places for bacteria. Another change was therefore made in the treat- ment of the machines, and the results obtained are given in Table (>. On these days the machines were rinsed with cold water as usual. They were then placed in water containing a small amount of pow- dered borax and boiled for at least one-half hour. The machines were then taken out and hung up in the open air until needed for use. EXPERIMENTS AT FARM NO. 1. 41 This treatment was given the machines on but two days. As shown in the table, the average for the machine-drawn milk was 28,562 and for the hand-drawn 48,125 bacteria per cubic centimeter. This is a much smaller number than had been previously obtained by either the machine or hand method, but the relative numbers are not materially different from those found in the previous series of experiments where the machines were soaked in brine. These results seem to indicate that the boiling in a weak borax solution and the soaking in the brine were about equally effective in freeing the machines of bacteria. TABLE 6. Comparison of results of hand and machine milking machines rinsed with cold water, boiled m water containing borax, then hung up 'in open air till used. Aug" s t Date. No. of experi- ment. f 95 I 9(5 ( 101 I 101 A Time of milking. Night... Method of milking. Number of bacteria per cubic centimeter of milk. Hours to c dling at ir- Total bacteria. Acid bacteria. Liquefy- ing bacteria. 70 F. 50 30 ! 41 ! 54 F. Machine . 35,125 4,625 9, 125 3,000 o 13, 500 11,125 16,625 4,500 17,000 86 96 111 . ...do Hand 45 000 do . . Machine 22, 000 7 .S75 do do Averages 102 do Hand 51,250 43 75 (Machine 28, 562 48, 1-25 3, 812 11,312 7,812 16,812 42 42 99 86 Percentages. (Machine 13.4 23.5 27 4 35.0 (Hand [ 1 a Curdled at night exact time not determined. ForHTII TREATMENT OF THE MACHINES. On the night when samples 101 and 102 were taken, a third sample marked in the table "101A" was obtained b\- milking two cows into a machine, all parts of which had been placed in a box and subjected to live steam for 20 minutes. The results obtained in this way are very striking. The number of bacteria contained in the milk thus taken was 7.875, while the number from the other machines was 22,000 and in the milk drawn bv hand 51.250. FIFTH TREATMENT OF THE MACHINES. At this point another change in the treatment of the machines was made. After being used at night they were rinsed with cold water, then washed with hot water, without the addition of any borax. The results obtained when the machines were thus treated are'sdven in m Table 7. After the morning milking the machines were rinsed with cold water as usual. They were then washt in hot water contain- ing borax, after which all the rubber parts were placed in brine until needed for the evening milking. The results obtained from this treatment are shown in Table ( S. 42 THE MILKING MACHINE AS A FACTOK IN DAIRYING. TABLE 7. Comparison of results of hand and machine milking machines washt in cold water and then in hot sal soda water, no borax being used. Date. No. of experi- ment. Time of milking. Morning do Method of milking. Number of bacteria per cubic Hours to cur- centimeter of milk. dling at Total bacteria. Acid bacteria. Lique- fying bacteria. 70 F. 50 F. August August August August August August August A P( 8 9 1 97 \ 9* ( 103 '1 104 j 109 I 110 1 115 '1 116 ( 121 . Machine Hand . 268, 666 296 250 49, 666 122, 000 500 28,000 2,000 5,875 5, 125 15, 750 7,125 326, 000 4,000 4,625 1, 625 2, 375 77,999 103, 375 625 32, 250 4,125 19, 375 6, 625 9, 625 9,250 92,000 6, 375 1,525 3,000 250 37 28 38 32 35 30 37 37 a 41 26 35 35 a 41 35 83 63 96 63 58 41 "65 a 65 () a 41 (") ( & l ( 6 ) '< do.. . Machine 5, 875 10 do., do . Machine Hand .: 14,000 102 9 50 do.. . Machine 72^ 375 ' 54 625 12 do Hand do.. . Machine .! 64,125 13 1 122 f 127 ) 128 f 133 1 134 do .. do.. .] Hand . Machine 944, 000 84, 375 do.. . Machine 76, 750 do Hand 42, 625 /Machine S3, 738 10,006 15,42* 38 78,089 3.5,914 32 70 58 >rcentage. ' \Hand (Machine 12.0 18.2 32. _> 16. 5 "Curdled at night exact time not determined. '>Xot curdled by August 19. In four of the experiments shown in this table the machine-drawn milk contained a much smaller number of bacteria than did the corre- sponding- hand-drawn milk. In some of these cases the difference is very great, es- pecially in experiments 103 and It)!, and 1<>1> and 110, where the numbers in the machine-drawn milk were small. In the other three experiments, however, the machine-drawn milk con- tained larger numbers of bacteria than did that drawn by hand. Still, the averages are decidedly in favor of the machine- drawn milk. The results obtained from the night's milk where the machines were washt in borax water and soaked in brine will be found in Table S. EXPERIMENTS AT FARM NO. 1. 43 TABLE 8. Comparison of results of hand and machine milking machines wasld in cold water, then in borax water, ) 50 CM I 108 I 113 113A 114 119 ll't \ do Hand . . do Machine do do \ugust 1 1 do Hand do Machine d ) do 120 125 V>5 \ d > Hand d >.... Machine d > do 1 126 | 131 \ 132 1 137 < 137A 1 138 d > Hand d ..... Machine August 14 do Hand do Machine do do Average. do Hand (Machine 225,917 6,250 12,975 1,275 58,500 , 16,625 8,125 42 w 1,733 61 > 13,812 j 41 66 {Machine A . (Hand 9 '.' :> (i {Machine -V 13 4 [Hand 28. 4 23. 6 "Curdled in night exact time not determined. , curdled by August 19. In a part of those experiments the results are very much in favor of the machines, while in the last three tests the comparison is in favor of the hand-drawn milk. This seems to be due to an unusually small number of bacteria in the hand-drawn milk rather than to any marked increase in the number in the machine- drawn milk, with the one exception of experiment 181. In this case 1 it is evi- dent that something decid- edly wrong must have oc- curred to give the milk such an abnormally high germ content. If we leave this one experiment out of the averages we have for the machine-drawn milk an av- erage of 28.500, instead of 225.900, and for the hand-drawn mi!k 00.225. instead of This would o-ive a showing greatlv in favor of the machines. & CJ <^ * case in the preceding tables. per 58.500. is is the 44 THE MILKING MACHINE AS A FACTOR IN DAIRYING. TREATMENT OK THE MACHINES. In connection with the experiments shown in the preceding table, '2 cows were milked each night with a machine which had been sub- jected to live steam for '20 to 80 minutes. The results of the milk thus obtained are seen in the experiments marked "A" in the table. It will be seen that the numbers of bacteria in this milk are very much smaller than those obtained by the other machines, running as low as 2,875 bacteria per cubic centimeter in experiment 107A. These results seem to indicate that, even with the care that the regular machines were receiving, they still harbffred relatively large numbers of bacteria which contaminated the milk drawn thru them. It will also be noticed that, even with the machine receiving the steam treatment, the germ content of the milk increased quite rapidly from day to day until it was about, the same as in the regular machine-drawn milk. This is regarded as an indication that the steam treatment given was not suf- ficient to completely sterilize this machine, so that the bacteria gradu- ally accumulated in the tubes. It was not possible to get any pressure in the box used for steaming this machine, and it is very probable that the temperature of the inside of the long rubber tubes did not reach that of the steam, and hence did not become sufficiently heated to kill the bacteria in them. KEEPING QUALITIES OF THE MILK. As stated at the beginning of this discussion, an attempt was made to determine the keeping qualities of the milk by taking two subsam- ples as soon as the milk reached the laboratory and keeping one of these at a constant temperature of 70 F. and the other at 50 F. During the day these samples were watched and the time at which they curdled was recorded. It was, of coursc.*impossible to watch the samples during the night, so that in the case of many of them the exact time of curdling could not be determined. Where the samples curdled during the night the time of curdling was arbitrarily given as midnight, and all such results are indicated in the table. The temperature of 70 F. was taken as representing fairly well the ordinary room temperature during the warm season, and that of 50 F. as representing the normal temperature of the refrigerator in the household. The records of the time of curdling for the different samples are given in the various tables. It is not always easy to determine why a certain sample of milk should curdle when it does. In general, nor- mal milk becomes sour and curdles in proportion to the number of bacteria contained, but this relation is true only between wide limits. Not infrequently one sample containing twice the number of bacteria contained bv another will remain uncurdled the longer SUMMARY OF EXPERIMENTS AT FARM NO. 1. 45 time. There are, therefore, marked irregularities when we attempt to harmonize the keeping quality with the germ content. However, taking a series of samples containing a high germ content and compar- ing with another series with a comparatively low germ content, it will lie found that there is an inverse relation existing between the germ content and the keeping quality. Frequently the species of organisms which the milk contains has more to do with determining its keeping quality than does the actual number of bacteria which may be in the milk. This fact accounts for man}" of the apparent discrepancies between the germ content and the keeping quality. While the results given in the preceding tables show many irregularities, yet they are of considerable interest, and in the long run are of value as an indica- tion of the keeping quality of the different samples of milk. Sl'MMARY OF EXPERIMENTS AT FARM NO. 1. In Table 1) arc given the averages for the germ content and keeping- quality from the six preceding tables. While these averages are not of as much value as the results of the individual experiments, they give in a general way the relation existing between the machine-drawn and hand-drawn milk. It will be noticed in this table that there is a difference in favor of the keeping quality of the machine-drawn milk, both in the samples kept at 70- F. and in those kept at 50 F., the greater difference in favor of the machine milk being shown in the samples which were kept at 5o F. One important fact which is shown in this table is the greatly increased keeping quality of the milk which was drawn into the steam-sterilized machine marked "A" in the table. These samples held at 70- F. kept on the average one-third longer than the average of the ordinary machine-drawn or hand-drawn milk, while those held at 50- F. had not curdled by August 11) when the test ended. This emphasizes the importance and indicates the possibilities of greatly increasing the keeping quality by thoroly sterilizing the machine. 46 THE MILKING MACHINE AS A FACTOR IN DAIRYING. EXPERIMENTS AT FARM NO. 2. The conditions of cleanliness existing in this stable are considerably above the average (fig. (>.) From a sanitary standpoint this stable was not as well constructed as was the one at farm No. 1. The stable is entirely below ground on the west and north sides, but receives a good supply of light from the south and east. The feeding alley and mangers are made of cement, but the stable floor, the drop, and the main floor behind the cows are made of plank. While the construction of the sta- ble itself is not especially suited to the production of clean milk, considerable care was taken to keep the stable and the cows as clean as possible. Considerably more than average care was exercised in the milking and the subsequent han- dling of the milk, so that this stable may properly represent a fairly sanitary dairy. It is not to be ex pected that the germ con- FIG. 6. Bacteria in atmosphere of barn at farm No. 2. . . Drawing from photograph of gelatin plate exposed for tent OI milk produced 111 ^iif-h i sflble Could' be l~er)t as low as m a stable con- structed on more approved sanitary plans, but the number of bacteria found in the hand-drawn milk, as given in the following tables, shows, however, that the sanitary conditions of the stable at milking time were excellent. The stable floor was always swept twenty minutes to. one-half hour before milking was commenced, and just before milking, the udders were wiped with a damp cloth. METHOD OF EXPERIMENT. In beginning the experiments in this dairy it was desirable, first, to ascertain the relative germ content existing in the machine-drawn and hand-drawn milk. For this purpose the herd was divided into two lots of 4 cows each. One of these groups was milked by the machine and the other by hand into an open pail in the ordinary way. As soon as the mi Iking was completed, samples were taken from the mixt milk of each group of cows and these were carried to the labor- atory for testing. The details of these experiments are the same as those a 1 read}* outlined in connection with the experiments at farm twenty seconds in stable at milking time, showing the low germ content of the atmosphere, 34 colonies per plate. EXPERIMENTS AT FARM NO. 2. 47 No. 1. In this series of tests samples were taken at the night milk- ing only and were placed on ice until the next morning, when the plate cultures were made. It is probable that the tigures given in the tables are slightly lower than would have been obtained had the samples been plated immediately, since there is usualh r a dropping out of cer- tain species during the first few hours after drawing the milk. In a few cases where the samples were plated at night and again the next morning this was shown to be true. FIRST TREATMENT OF THE MACHINES. At the outset it was desired to ascertain the efficiency of the milking machine with the treatment it was regularly receiving on the farm. Three days' tests were made without altering the treatment which the machines received and the results were compared with those obtained from the corresponding samples drawn by hand. The results of these tests are given in Table 10. TABLE 10. -Comparison of results of hand and machine milking machines rinsed with cold water, v;asht with warm water containing sal soda, then rinsed, with hut tauter. Date. Num- ber of Method of experi- milking, ments. Bacteria per cubic centimeter of milk. Hours to cur- dling at During this period the machines were treated as follows: After milking they were rinsed by pumping cold water thru them. This was followed \)\ warm water containing some washing powder, com- monly sal soda. Thov were then rinsed with clean hot water and huno- - > O up in the air until needed for use at the next milking. A o-lance at L ~ the *' Total bacteria" column in the table shows the same relation exist- ing between the bacteria found in the hand-drawn and machine-drawn milk as was found in the experiments at farm Xo. 1. The number of bacteria in the machine-drawn milk was decidedly higher than in the corresponding hand-drawn milk in each experiment, the average for the three samples of machine-drawn milk being 172,!).")S bacteria per cubic centimeter, while the average for the hand-drawn milk is 9, -tod. It will also be seen that the organisms in the machine-drawn milk wore largely acid-producing species. This also corresponds to the conditions 48 THE MILKING MACHINE AS A FACTOR IN DAIRYING. found at farm No. 1. It is evident that the milk became contaminated with large numbers of acid-producing- organisms while passing thru the machines. These results seem to prove beyond question that the care which the machines were regularly receiving was not sufficient to keep the tubes in a sterile condition and they had therefore become breeding places for bacteria, which were washt into the milk when the machines were used. SECOND TREATMENT OK THE MACHINES. At this point a slight change was made in the method of treating the machines, and the figures given in Table 11 show the results of two days' tests with the machines thus treated. TAHLE 11. Comparison of results of hand and machine milking treatment of machine the .mmeas indicated for Table 10, except that it fas scalded just before use hi/ pumping boiling ivater thru it. Date! No. of experi- ment. Bacteria per t Tl ubic centimeter of milk. ours to cur- dling at Method of milking. Total bacteria. Ac id bac- teria. Per cent of acid bacteria. Liquefy- ing bac- teria. Per cent of lique- 7Q lying bacteria. D F. 50 F. J ill v 2-1 f 13 Machine... Hand Machine.. . Hand 22ti, 700 11,850 12.1100 1,100 8,883 2, GOO 4,98S 175 3 22 42 43 2. 287 250 487 112 1 4 10 70 130 b 54 b 102 97 171 64 171 July 2ti Average . 1 21 - \ 22 (Machine.. . 119,350 ti, 935 1,387 87 151 59 ! 137 a Udders not washt. ''Curdled at night exact time not determined. The machines were washt as previously described, but they were given an additional scalding just before being used by pumping boil- ing water thru them. It was hoped that this might dislodge and wash out any bacteria which might have accumulated in the tubes during the day, thus reducing the germ content of the milk. This additional scalding, however, apparently had little effect upon the condition of the tubes, since the numbers of bacteria were not materially decreased, as will be seen by a study of Table 11. Both the total number and the number of acid-producing organisms and also the liquefying bac- teria continued to be much more numerous in the machine-drawn milk than in that drawn by hand. It will be noted that in experiment 13 the udders were not wiped with a damp cloth previous to milking. This fact, no doubt, at least partially accounts for the high numbers of bacteria found in this lot of milk. EXPERIMENTS AT FARM NO. 2. THIRD TREATMENT OK THE MACHINES. 49 After being washt as previously described, the rubber tubes and teat cups were placed in water and boiled for three-quarters of an hour. They were then hung up in the open air until needed for the next milking. Just before using they were rinsed as in the previous experiments by having boiling water pumped thru them. Table 1:4 gives the results of four tests taken with the machines thus treated. TAHLE 12. Comparison of results of hand and machine milking machines ringed irith cold water and washt with sal soda, then boiled for tltree-quarters of an hoar and ringed with boiling water just before use. Date. No. of experi- ment. Method of milking. Bacteria per cubic centimeter of milk. Total Acid I Y. c ? 1 , t Lil r lU , t ; fy - unique- bacteria, bacteria, i ,ll;l!i tArin fyinff bacteria. Hours to cur- dling at 70 F. .50 F. Julj Julj Julj Julj Ave ''7 f 29 \ 30 \ 35 \ 36 f 39 i 40 f 47 i 48 Machine Hand.... Machine Hand.... Machine Hand.... Machine i Hand [Machine \Hand 18,737 5, 612 6, 537 85, 700 7, 175 3,025 125 50 462 82, 950 75 16 10 1 7 97 1 612 137 100 50 1,750 2, 200 3 18 2 1 3 91 126 144 a 54 ((78 50 "54 52 74 a 150 "54 a 126 134 87 102 171 28 29 . 10, 350 3, 050 30 1,000 9 36, 683 6,211 28,675 .. 1,231 91 71 91 133 985 . . 847 1 "Curdled at night exact time not determined. This increased treatment of the machine apparently was not sufficient to greatly change the quality of the machine-drawn milk. However, in experiment o~> the number of bacteria in the machine-drawn milk was somewhat less than in the corresponding hand-drawn sample. It should be borne in mind that the numbers of bacteria obtained by the hand milking are extremely low for milk drawn into an ordinary open pail. These low numbers of bacteria found in the hand-drawn milk emphasize the fact that the atmosphere in the stable was relatively free from organisms, and that considerable care was exercised in the drawing and handling of the milk. The man who did the milking was unusually careful in all his operations. In experiment o!J the rubber tube connecting the pulsator with the stanchion cock was not boiled with the other tubes, and it is probable that this furnished the source of contamination and explains the very high number of bacteria in this lot of milk. In order to determine whether the rubber tubes were responsible for the larger numbers of bacteria in the machine-drawn milk a new set of tubes was used in experiments (>:-> and (!!). These new tubes were washt and then scalded, together with the rest of the machine, just be- fore using. This resulted in a smaller number of bacteria from the machine-drawn milk than had been previously obtained. 50 THE MILKING MACHINE AS A FACTOR IN DAIRYING. TABLE 13. Comparison of results of hand and machine milking new tubes and teat cupx used, and machines washt as nsual and scalded just before using. Date. Num- ber of experi- ment. Bacteria per cubic cent meter of n Liquefy- ing bac- teria. lilk. Hours to cur- dling at Method of milking. Total bacteria. Acid bacteria. Per cent of acid bacteria. I'er cent of lique- fying bacteria. 70 F. 50 F. August '2 1 (13 Machine Hand... Machine Hand... /Machine (Hand... 3. 625 650 M,637 1,344 162 275 925 150 4 42 58 12 S7 25 25 144 2 4 1 11 86 161 50 a 102 a 126 206 116 i 126 August 3. .. \ 64 | ti9 Averages . . ' \ 70 2,631 543 j 997 212 55 68 132 121 166 "Curdled at night exact time not determined. wo jets of foremilk removed. The results of these tests as shown in Table 13 would make a very good showing- for the machine were it not for the fact that the num- bers in the hand-drawn milk were so extreme!}' low. However, it ought to be possible to obtain milk by means of the machine which would contain a lower germ content than hand-drawn milk under the same conditions provided the parts of the machine thru which the milk past were sterile at the outset, since the milk drawn by means of the machine is entirely shut off from external contamination. It ought to be possible to obtain the milk in the pail with practically nothing but the bacteria which exist in the udder. This manifestly was not the case with the trials made thus far and it was evident that still greater care was necessary in order to completely sterilize the machines. In order to determine the real condition of the inside of the tubes a test was made at this point to rind out whether or not the inside of the rubber tubes was being sterilized by the treatment given them. A small quantity of sterilized water was run into the central part of the long rubber tubes and rinsed back and forth. This was then poured out and a drop of this water inoculated into a gelatin plate. This resulted in the development of 1.728 colonies of bacteria as the germ content of a single drop of the water used for rinsing the tube. This showed beyond a doubt that the inside of the tubes was not being properly cleansed and sterilized by the treatment thus far used and that greater care was necessary in order to overcome this trouble. KOl'KTH TREATMENT <>F THE MACHINES. The writer desired especially to test the efficiency of the machine for the production of sanitary milk, or milk containing a minimum germ content. It was therefore decided to take still more vigorous moans for cleansing and sterilizing the machines. To do this, in addi- tion to the treatment usually given, the tubes were boiled for three- quarters of an hour in water containing a small quantity of powdered borax. Thev were then thorolv rinsed with boiling water to EXPERIMENTS AT FARM NO. 2. 51 remove any traces of borax which might be in the tubes. A small amount of borax was also added to the water used for wiping off the udders. In addition to these precautions a small amount of foremilk was also drawn before attaching the machine to the cows, and the pail was carried out of the stable before the cover was removed. This treatment proved to be more effective than any previously given, as will be seen b}< a study of Table 14. TABLE 14. Comparison of results of hand and machine milking machines rinsed with cold water, washt with warm water containing sal soda, boiled three-quarters of an hoar in water with borax, and scalded just before use; udders wiped with borax water. Date. exDeri Mctho<1 of me P n[.'" milki '^ Bacteria per cubic centimeter of milk. Hours to cur- dling at Total bacteria. A -j Percent bacteria of cid bacteria. bacteria _ Liquefy- ing bac teria. Per cent of lique- fying bacteria. i 70 F. 50 F. . I 75 Machine . Au g st 4 \ 76 Hand. . . iiurnsr 5 i sl Machine . Au ust 5 \ 82 Hand... . t 87 Machine . I 88 Hand... Averages . (Machine . 462 1 550 400 - 881 612 1 , 300 62 i 115 49 139 123 : (a) ^54 , (a) 1>7S 124 48 100 225 , 15 12 3 81 9 112 18 75 (i 419 25 37 80 28 6 6 6 506 1,090 62 31 40 88 120 50 i 120 IHand. .. . 78 a Not curdled by August 19. ''Curdled at night exact time not determined. It will be noticed in this table that the machine-drawn milk con- tained in each case much smaller numbers of bacteria than did the corresponding hand-drawn milk. These numbers compare very favor- ably with the germ content of the best grades of "'sanitary" or ''clinical'' milk which are now placed upon the market. In fact these numbers are below the germ content of much of such milk. The results of these tests are sufficient to prove that the germ content of milk can be reduced to a very low figure by the use of the machine when properly sterilized. While the boiling in borax water was apparently an effective treatment, attention should be called to the danger of using this or other antiseptics to rid the rubber tubes and teat cups of bacteria. A very thoro rinsing of the tubes is necessary in order to remove all traces of the antiseptic so that none of it can be taken up by the milk as it passes thru the machine. If the antiseptic were left in the tubes it would be the same in effect as treating the milk with a preservative a practise that is considered very objection- able. There was also some 1 question, in regard to the effect of the boiling upon the life of the rubber tubing, and it was some work to boil the machines in this way each clay. For these reasons it was thought desirable to find a simpler way of sterilizing the machines and one which would not have an injurious effect upon the rubber. 52 THK MILKING MACHINE AS A FACTOR IN DAIRYING. FIFTH TREATMENT OF THE MACHINES. Common salt is a good germicide, and it also has a hardening and preservative effect upon the rubber. It was therefore thought that possibly a brine solution might be used for sterilizing the rubber tubes instead of boiling them in borax water. To test this the machines were washt as usual, after which all the rubber parts were placed in a moder- ately strong brine solution, where they remained until needed for the next milking. Before being used the^y were thoroly rinsed by having boiling water pumped thru them. Table 15 gives the results of the tests made with the machines thus treated. TABLK 15. Comparison of results of hand and machine milking machines being washt as usual, the rubber parts then placed in brine till needed, and scalded just before rise. Date. No. of experi- ment. Method of milking. Bacteria per cubic centimeter of milk. Hours to cur- dling at Total bacteria. Acid bacteria. Per cent of acid bacteria. Liquefy- ing bac- teria. Percent of lique- fying bacteria. 70 F. 50 F. August 7 1 98 Ma Ha Ma Hi Mi Hi fMi IHi chine., id thine., id 'hine.. id thine., ul 6, 450 4,075 400 600 483 18,750 475 5G2 112 100 100 1 , 350 7 11 28 1(1 21 (525 363 100 33 1, 149 10 9 "o 8 52 54 48 08 101 "78 100 " 102 109 121 C'i I'O August s \ 94 I 1)9 \ugust y i 100 j 105 \ loo 2, 444 11,712 229 1 , 000 2r>3 67 (17 105 112 604 ('Curdled in night exact time not determined. ''Not curdled August 19. It will be noticed that in experiment !>> the number of bacteria was decidedly higher than in the preceding test* given in Tables 13 and M, while in experiments 9i) and 105 they were as low as when the machine was treated with borax. Probably the higher number in experiment 93 was due to the fact that only part of the rubber tubes were treated with the brine solution, while on other days all the rubber parts were placed in the brine. It would seem from the results of these tests that the brine treatment is as effective as the boiling in borax water and is at the same time much simpler. SIXTH TREATMENT OF THE MACHINES. The usual method for sterilizing dairy utensils is by steam. This is entirely satisfactory with ordinary dairy utensils, but steam is known to have an injurious effect upon rubber, for which reason steam ster- ilizing \vas not generally used in this series of experiments; but at this point it was doomed desirable to compare the efficiency of steam ster- ilizing with the treatments previously given, in order to determine whether or not it was possible to reduce still further the germ content of the machine-drawn milk. To accomplish this a large wooden box EXPERIMENTS AT FARM NO. 2. 53 was fitted up to serve as a steam sterilixer. After the machine had been washt as usual, it was placed in this box' and subjected to live steam for 30 minutes. Table 16 gives the results of this series of tests. TAHLE 1<>. Comparison of results of hand and machine milking machines washt as usual and sterilized in steam for thirty minutes. Bacteria per cubic centimeter of milk. Hours to cur- dling at Date. ber of Method of experi- milking. merit. Total bacteria Acid bacteria. Per cent of acid bacteria. 1 ioiiffv ' 1>er cent ing of lique- 70 F. 50 F. August 10 / 111 Machine.. 1 112 Hand... 560 400 37 112 7 28 77 158 gj 75 19 . ,1 117 Machine.. A "S US1 u \ 118 Hand 1, 962 1,762 337 375 18 22 75 4 287 17 69 '30 60 AUS-U2 { } Machine. 1,087 850 137 14 100 12 75 7 112 13 45 49 (j Aup-tu { ijg S h : e : 9,887 5, 540 225 2 860 10 375 4 250 I 5 <) (i < ,, , 1. ( 135 Machine . 3, 750 387 10 162 4 ft 54 (") I 136 Hand... . 1,337 362 28 275 21 () () Average-; .(Machine. . 3,449 1,978 225 362 137 64 \Haud 200 79 n\ot curdled August 19. Curdled at night exact time not determined. It will be noticed that in each test the machine-drawn milk contained larger numbers of bacteria than did the corresponding- hand-drawn sample. It was impossible, with the equipment used, to get any pressure in the steam chest, hence the temperature did not quite reach the boiling point (212 F.). Under these conditions it is probable that the inside of the rubber tubes did not become heated to the tem- perature of the steam, and they, therefore, were not sterilized during the thirty minutes that they were subjected to the steam treatment. Probably a longer steaming might prove effective, but it is evident that the treatment here given was not sufficient to completely sterilize the tubes. The rubber tubing did not appear to be seriously injured by the steam treatment during this series of tests, but it is quite prob- able that long-continued steam sterilizing would injure the rubber. This series of tests would at least indicate that it is necessary to sub- ject the tubes to greater steam pressure or else use other germicides in order to completely sterilize the rubber tubing. At the close of this period one test was made by treating the machine in brine, as alreadv described. The results of this test are shown in Table IT. TABLE 17. Comparison of results of ham! and machine milking machine* t/-rate. ]>oth the total number and the percentage of liquefying bacteria found in the milk were in most cases greatly reduced by the use of the machines. This fact is of special significance in milk designed for direct consumption. 7. When properly cared for. drawing the milk by means of the machine increases its keeping quality. SUMMARY OF BACTERIOLOGICAL INVESTIGATIONS. 55 8. Washing the machines with cold water and then with hot water containing sal soda is not sufficient to keep the rubber tubes clean. Under this treatment the inside of the tubes becomes coated with decay- ing- milk, thus forming; ideal conditions for the multiplication of various species of bacteria. 9. Scalding the machines by pumping boiling water thru them just before use had little or no effect in reducing germ content of the milk. 11). Boiling in clear water for three-quarters of an hour was not suf- ficient to keep the rubber tubes in a sterile condition. 11. Subjection to steam without pressure for thirty minutes was not sufficient to sterilize the rubber tubes. 12. Placing the rubber parts in brine for several hours after being washt reduced the germ content of the machine-drawn milk to about one-half that of the milk drawn by hand. 13. Boiling in water containing a small amount of powdered borax had about the same effect in reducing the bacterial content of the milk as did the brine treatment, but the use of borax is dangerous unless extreme care is exercised. 14. The machines may be veiy effective in the production of sani- tary milk if they are properly cleaned and sterilized. 15. The results of these experiments indicate that the machines may be kept in such an insanitary condition that the keeping quality will not be improved, but may be seriously impaired. They also indicate that with properly cleaned and sterilized machines the keeping quality of the milk may be very materially improved. O 001 120 178 7