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Mechanical Milking.*
Mechanical .Milking
355
had been swa bbed with lachry mal disch arge from a beast dying of .acute rinderpest . This single experiment is against the tra nsmission of rinderpest by house-flies passing from ey e to eye. CONCLUSIONS. The thick , stra tified , squamous ep ithelium which covers the skin , and lines the mouth , <:esophagus, etc ., is ample mechanical protection aga ins t the penetra tion of rinderpest v irus from outside ; so tha t infection does not occur across t he unbroken skin , and if occasionally by the mouth, then only by penetra tion of t he wall of the pha ryn x or after the virus has passed t he fi rst three stomachs. The transitional ep ithelium of th e conj unctiva is not a n effi cient barrier, a nd the stra tifi ed , cy lindrical epithelium of the t rue nasal mucous m embra ne is passed wi th ease. It is probable t hat t he v ir us ma kes th e passage of such epithelia within or attached to wandering leu cocytes. Sources of in fec tion a re con fined to th e bodies a nd fresh excre tions of animals a ctu ally sufferi ng from rin derpest . The possibility of tra nsmission of rinderpe t by blood -sucking fl ies h as been dem onstrated experimen tally, but much observation in the fi eld will be necessary before it ca n be stated wh et her at certain seasons such in sect s a re importan t tra nsmitters. In nature, t he commonest way in which th e disea se is c:; pread is probably by direct contact of t he n asal m ucous membra ne with infec tive excretions. ME CHANICAL MILKING .* By DR. GALLI A.
I N a n a rticle which I wro te under the above heading in the
Agricultural S cientific Paper for Czecho- lovakia (No. 11 of t he 10th April, 1925), I said t ha t I was n ot a t tha t time in a position to be able to express any defi nite opinion u pon the advantages or disadvantages of milking m achines, or , indeed, with regard t o the advisability of using m echanical milking a t all. If an y opinion is to be expressed about mechanical milking, it is absolutely n ecessary to make accura te compa rative test s between m ilk which has been drawn b y hand , a nd milk which has b een d rawn t hro ugh a m achine . Bact eria and m ould funguses have th e most active effect on milk . For t his reason th e ca re taken in drawing milk and storing it under t he most scrupulously clean conditions is of the utmost importa nce if th e milk is required to be kept for any length of time. * Abstract from Th e S cientific Agricultural P ap er. Czecho-Slovaki a.
356
The Veterinary Journal
Up to 100,000 bacteria per cubic centimetre is quite u sual in milk which h as heen drawn by hand. All th e changes which th e milk undergoes after it has left the udder are of bacterial origin . T r.erefore, to show how bacteria can be excluded from milk is of great practical importance to the milk producers and t o the ret ailer. In any case, it is of t he grea t est importance to have as few germs in the milk as is possible. Germs which enter the milk during t he process of milking come fro m the dry hairs of the udder and are shaken into the milk pail as the hand works on the t eat. Hay dust , small particles of foodstuffs, dirty milk vessels and especially the dirty h ands of milkers, consti tu te the principal sources from whence contamination arises. Very careful method s have to be adopted if milk with a low bacteriological content is to be produced . The actual constituents of milk are affected by the breed of the animals (each with their own peculiarity), the point in the period of lactation when the milk is drawn , the sexual activity, the food, exercise taken, the warmth and general comfort or otherwise of the cowsheds; but most particularly th e manner in which the actual milking is accomplish ed. As the period of lactation advan ces, the amount of fat to be found in the milk generally increases. The last milk drawn (known as the s trippings) is always richer in fa t than the first milk taken . F or this latter reason, only that milk which has been regularly milked right out to the last drop is known as " bes t milk " in the milk trade. It is clear, therefore, that a ttention must be paid to uninterrupted and complete milking out of the udder and consequently the solution of this problem is to be found in a machine which is absolutely precise and regular in its action . The quantity of milk drawn is also of the greatest importance. I t is only possihle to det ermine which method of milking is t he most productive by m aking an exact comparison of the amount of milk obtained b y each method. Such a comparison must he made throughout the whole of a lact ation p eriod, or at the least over several months, and then not only of milk obtain ed from one cow, but from a great number of cows, each in tl:e same period of its lact ation , or otherwise an increase or a decrease in milk yield can be attributed to other causes than that of the method employed of milking the cows. Hand milking is an unn atural proceeding. That is obvious and is impossible t o deny. If the sucking of the calf on the t eats is h eld to be the natural way of emptying the udder, then the process of hand milking is quite different and consequently must be unn atural.
Mechanical jl,lilking
357
Because the bulk of the milk is secreted by the cow during the actual process of milking and because she possesses the po\yer to stop this secretion if she is unsatisfied or otherwise dislikes the process of milking, therefore the amount of milk obtained depends principally upon the skill of the milker. The importance of the way in which the milking of a cow is done is proved by the numerous schools of thought which exist as to how, precisely, hand milking should be accomplished, and the courses at different colleges which are held to teach the theory and practice of milking. T aking into consideration the fact that each hand milker on a farm has of necessity to milk a number of cows, then it will be agreed that it is only the conscientioLlS milkers who will milk out completely every cow. When milking a number of cows, the hand milker is apt to get tired and consequently becomes careless and sloppy in his milking. For this reason the act of milking cannot be as pleasant for the cow as it really would be if she were milked in a natural way. Another result is that the quantity of milk obtained will be less than which is actnally possible. A milking m achine can be made which is absolutely uniform in its operation and soothing in its action. The factor of fatigue of the opera tor cannot affect the cow. Provided that the construction of the apparatus is based upon the act of sucking of the calf, which is the fu ndam ental and natural method of milking a cow, then a milking machine will be preferable to a hand-milker. I would observe that cows which have shown themselves t o be restless when hand milked very soon and easily become accustomed to a good milking machine. As regards the complet e milking dry of the animal it must be remembered that the lactic gland s are always secreting milk. This milk will collect in the milk cisterns, so that even if the milking has been very completely carried out, nevertheless, in a very short while after milking is over it will be possible to draw off further milk. It is true, th erefore, that theoretically a cow can never be milked right out . From experience, however , it can be shown that prolonged stripping of cows is not profitable. When stripping the cows is recommended after the machines have been taken off, it is done in order to ensure that a regular inspection of the teats is carried out. Nineteen cows in milk were selected and given index numbers in order t o carry out experiments for judging between both ways of milking. They were put on a farm at Blanda. Commencing on July 1st, 1925, samples of milk were tested in respect of their quality as well as quantity . The results are shown on the following table. From this Table it will be seen that from July 1st to September 27th
The Veterinary Jourl1al
358
t ests were made from hand drawn milk , and from September 28th t o 12th Octob er from machine drawn milk. During th e period of hand milking the following food was given ' A. Green food as much as the cow would eat. B. 2 Kgs. mixture of : 1 Kg. bran. t Kg. malt. 1 Kg. oil cakes. 11 Kg. barley meal. During the period of m achine milking the food consisted only of beetroot leaves (sugar refin eries), and a t night barley straw was m ixed with them . COMPARI SON BETW EEN H AND AND MACHI NE MI LK I NG OF 19 COWS . (a) By
H AND M ILK I NG .
Daily Record . Date
...
1/ 7
2/7
3/7
4/7
5 /7
6/7
7/ 7
8/7
9 /7
10 / 7
-- -- -- -- -- -- -- -- -Milk in Litres Fat Content %
163·0 163·0 160 ·5 169·0 159·5 165 · 5 158·5 158 · 0 158·5 157· 5
-- -- -- -- -- -- -- -- --
-- - -
-- -- -
- -- -- -- --
Maxim u m Variation in Fa t Co n tent % ... Date
...
14/7 15 /7 16/7 17 /7 20/7 27 /7 3 /8 10/ 8 -- -- -- -- -- -- -- -Milk in Li tres 150·0 143 ·5 146·0 14 1 · 5 143 ·5 140 · 0 127 ·5 124·5 ------ -- -- -- -- -- -- -- -Fat Conten t %
17/8
122·0 11 6·
--
-- -- -- -- -- -- -- -M ax i mum Variation in Fat Co n tent % ... Dat e
.. .
3 1/8
7/9
14/9
21/9
Average .
-- -- -Milk i n Litres
135·5 147· 5 156 · 0 149 ·5
- Fat Con tent %
148·2
-- -- -4 · 19
-- -- -- -- ---M ax imu m V ari atio n in Fa t Co n t ent. % ...
0- 27
24/8
--
Mechanical Milking (b) By
MACHINE MILKING .
Dail y Record . Date ...
...
. ..
28/9
29 /9
-- - -
Mi lk in Litres Fat Content
%
30/9
I JlO
-- -- -
2/ 10
-
3/ 10
4/10
-- -
-
5/10
6/10
-- --
... 163·0 162 ·5 159 · 5 163·5 156·0 155 · 0 159·0 162·5 157 · 5 - - -- -- -- - - -- - - - - --
.. .
-- -- -- -- -- -- -- -- -
Max imum Va ri ation in Fat Conten t %
...
... / 7/10 8JlO 9/ 10 10/ 10 11 / 10 12f10
Average .
Mi lk in Litres
... 157·0 152·5 152· 5 156·5 156 · 5 159·0 -- - - -- -- -... - - - - - - - - - -.. - - - -
164·8
Date ...
Fat Co ntent
%
Maxim um Vari ation in Fat Con t e nt %
4·28
0·14
A comparison of the tables gives the following r esults : 1.
In the first place the great inconsistency between different cows· milked by hand is striking. This influences of course the total quantities per day from the 19 experimental cows. On the other hand you will see from the table of machine drawn milk how very constant is the total quantity of milk taken from the cows. There art:: no great fluctuations. 2. It can be shown that at the commencement of the hand milking experimen ts one or m ore cows showed a certain maximum quantity which later in the experiment fluctuated or dropped. Directly , h owever, the machine milking was b egun the old high level was obtained which is a sign that by m achine milking all the milk which the glands produced was drawn. 3. During the period of hand milking the feed for the cows was in every way stronger than it was during the period of machine milking. N evertheless, you will notice that the total quantity of milk in the later case was greater than in the first case. From the three observations made above the following can be drawn : l.
2.
conc1usion~
With milking machines the milk gland is always working uniformly and is always uniformly emptied. The milk gland is absolutely emptied, I.e., secretes all the milk it possibly can.
The Veterinary Journal
.360
We a rrive at similar conclusions by comparing the fat content in hand-drawn milk and that in machin e-drawn milk. In fact , we can go further and show that the far content in hand-drawn milk is s ubject to greater fluctuations than that of machine-drawn milk. You will notice that the difference between the lowest and the highest quantity of milk from the different experimental cows is greater i n the case of hand-drawn milk than it is in the case of machine-drawn milk. The a mount of fat in machine-drawn milk is a little greater than it is in hand-drawn milk, although, as I have pointed out above, the food given to the cows during the period of hand milking was inferior to that which was given during the period of inachine milking. This astonishing result can be explained by the fact that with machine milking the udder is milked out a nd the last quantities of milk contain
" 5 6
:Bottle No. 1 2 3 4
5
Bottle No . 1 2 3 4,
" 5
Right Front T eat. 96 g. Milk 84g. 90 g. 80g. 98g. 45g.
Amount of F at . 3'3% 3'7% 4 ·0 % 4'1% 4· 4°/' ,0 5'7%
Left Front Teat. 90 g. Milk 88 g. 84g. 78 g. 44 g.
Amount of Fat. 3·2 % 3'3% 3'4% 4·2% 5·2 %
Right Rear Teat. 87 g. Milk 89 g.
Amount of Fat. 3·1% 4,0% 5'9% 5'9% 8'5%
100 g.
92 g. 39 g.
Mechanical M ilking Bottle No.1 2 3
4 "
[) (j
Left R ear Teat. 86 g. Milk 87 g. 85 g. 78 g. 88 g. 78 g.
361 Amount of Fat. 2'5 % 2'6 % 2·8 % 2·9 % 6'8% 9'5%,
Th e teats were milked ou t one after the oth er and not simul taneously. Adjacent quarters would b e affected by this method with the result that a small quantity of milk would collect in the milk cistern of a teat which had alread y b een milked. Th erefore, the t eats were re-milked at the end of tbe milking of all quarters, with the result that 74 grammes of milk were obtained out of the four teats, having a fa t content of 7·1 %. This shows that the milk collected in the milk cistern during the day and the first drawn off is the poorest. The fat content of milk increases during milking, and you can sec fro m the above tables that the fat con tent rises as the milking proceeds. When putting all the milk together, it is this high fat content a t the end of milking which corrects the low fa t content a t the commencement. If a cow is not milked out carefully, therdore, the m ean content of fat in the whole milk quantity will be lower than it need be. For example, if this last drawn milk had been disregarded, then the average content of fat for the single teats would h ave been3 · 85 % 3·77 % 4'03% 3'56% But by adding the last drawn milk the corresponding average fat content is raised to-4'03 % 3·95 % 4 '46 % 4'49% and the average fat content for all four t eats t ogether would beWithout last drawn milk 3·83 % With " 4·24°/" It will be seen from the ahove that the fat content in milk is very dependent upon th e way in which the cow is milked. It is quite easy, therefore, to appreciate the common idea that results of milking vary in direc t proportion to the conscientiousn ess of the hand milker.
362
The Veterinary Journal
Because the fat content in machine drawn milk is higher than the fat content in hand drawn milk , it follows that the udder is better emptied in the former case. The chief quality required of commercial milk is tha t it shall keep sweet as long as possible. This is governed by the number of bacteria which enter the milk during the process of milking and s ubsequently. The b acteria which enter the milk do 110t commence their destructive action until after a defi nite period of incubation. The period of incubation in warm milk is from 38 hours and in milk cooled down ab out 10 degrees, it is bptween 52 and 75 hours. The precise time is dependent upon the number of bacteria present . It will be seen, therefore, that clean milk has an incuba tion period of about one to four times longer than dirty milk. Milk hygienically produced t akes double the time to curd tha n contaminated milk takes. In order t o compare hand milking with machine milking in so far as contamination of the milk was concerned , counts were taken of samples. Samples were taken once weekly of hand drawn milk and twice weekly of machine drawn milk. A furth er daily sample was taken to watch the results of the cleaning of the machines. B acteria colonies were counted, bred on OrIa-Jensen nutritive substratum, dilution 1-1 ,000. The counts of hand drawn milk were : -136 ' 000,152 ' 000,193'000 , 117'000, 149'000, 187'000, 158 '000, 126 ' 000, 134' 000, 172·000. The counts of machine drawn milk were : -11·000, 23 ' 000, 19 ' 000 , 28 '000, 35 '000, 33 ' 000, 41 ' 000. After the .first cleaning which has to b e repeated every week , the numbers of bacteria were 21 ·000, 26'00;), 24 ' 000, 31·000, 36'000 , 29·000, 34 ·000. There is no doubt. b ut that these counts could h ave heen reduced considerably by more careful cleaning of the teats and of the milking machine. The variou kinds of bacteria found in milk have different reactions on the milk. For instance, bacilli, acidi lactiti , bacterium coli, etc., ferment the milk and tum it into lactic acid, which in turn under certain conditions turns the casein into curds. Further experiments were carried out to discover whether machine milking excluded any particular kind of bacteria or whether milk drawn by a machine contained larger quantities of any particular bacillus than did milk drawn by hand. For convenience of comparison the milk was gr aded into four classes according to the time taken to bring about decolorisation. When any impurities such as food or particles of dirt were found in the milk, then it was classified one grade lower. .
Mechanical Milking
363
The results of hand drawn milk from 30 samples were : Grade I .. Nil. II 3 samples. III 18 IV 7 2 V The result of machine drawn milk from 21 samples wereGrade I 19 samples. II 2 These results are very favourable to mechanical milking and are obvious when you consider that mach ine-drawn milk never comes into contact with the air in the cowshed s. Further, the only impurities which can enter the milk are bacteria on the teats in the udder or on different parts of the machine. R eviewing the profits and working costs, the following data were s upplied to me by the Directors of the Mueglitzer Sugar Refinery. When hand milking was done the following staff were required at Blanda Farm :1 Head Cowman at K c. 22 per day = Kc. 22 6 H and Milkers Kc. 18 = Kc. 108 2 Assistants = Kc. 36 " Kc. 18 Total 9 Kc.16 6 Representing a Wage Sheet of Kc . 4,980 per month. Since the introduction of mechanical milking the following staff only are n ecessary:1 H ead Cowman at Kc. 22 per day = K c. 22 1 Second Cowman" Kc. 22 = Kc. 22' 3 Assistants " Kc. 18 = Kc. 54 Kc.98 Total 5 Representing a Wage Sheet of Kc. 2,940 per month . . To this last figure must be added the cost of power to drive the p lant, which for this particular farm was Kc. 650 per month . Total costs are therefore :. By Hand Milking Kc. 4,980 per month. " Mechanical Milking Kc.3,590 Saving Kc. 1,390 In addition , the increase both in quantity and quality of milk obtained, when mechanical milking is done, must be taken into consideration, and it will be seen what a good investment the plant reallv is.
364
The Veterinary Journal
Summarising the results obtained with the milking plant described above in * this journal, the following conclusions are reached. 1. The quantity and quality of the milk p roduced both show an improvement and a t the same time increased profits are obtained due to lowering of labour charges. 2. Milking with this plant is not injurious to the mammary glands, but is actually beneficial : t he unnatural action of h and milking is done away with and in its place a na t ural action is substituted very simila r to the sucking of t he teats by a calf. The milking is always uniform and eliminates the personal elements of inexperience, temper, etc., which occur with hand milking. 3. F inally, from a hygienic poin t of view, mechanical milking is ideal as contamination of the milk in the shed becom es p ractically impossible. I wish to express my very best thanks to Mr. Oskar Kunovsky, Professor in Chemi stry of the St aats-R ealgymnasium in Hohenstadt , for his extremely valuable support in this work ann especially for the carrying ou t of all the chemical t ests men tioned .
NOTES F ROM THE DISSECTING R OOM. By A . W. W HI TEH OUSE, M.A., M. R.C.V .S., Principal and Professor of Anatomy, The Veterinary College, Gla sgow .
SURGICAL R OADS TO THE P ARAPHARYNGEAL LYMPH GLANDS AND THE GUTTURAL POUCH IN THE H ORSE. TOGETHER with Captain H . S. Eakins, Veterina ry Corps, U.S.A., I reported (about 1!H 4) in wha t was then the .-\merican Veterina ry R eview, on a compara tively safe and very easy method of reaching these structures, and I have sin ce tanght this route to my studen ts in anat omy; but as very little notice seems to have been taken of our work , I take this oppor t unity of goi ng over t he ground again. Guttural POllch d isease must be very rare: I have seen one clinical case, which I always suspected to have been caused by opera tion, and in th e hundreds of dissections th a t I have looked at I have only found one diseased pouch, tha t bei ng an ex tension downwards from an old poll-evil of t he indura tive type. On the contrary, paraphary ngeal abscess is p retty common in strangles and th e sym ptoms are often alarming.
* Th e m il ki ng machi ne described i n the above abstract was the AlfaLaval Mi lk cr.- EDITOR ,. VETER I NARY J OURNAL ."
355
had been swa bbed with lachry mal disch arge from a beast dying of .acute rinderpest . This single experiment is against the tra nsmission of rinderpest by house-flies passing from ey e to eye. CONCLUSIONS. The thick , stra tified , squamous ep ithelium which covers the skin , and lines the mouth , <:esophagus, etc ., is ample mechanical protection aga ins t the penetra tion of rinderpest v irus from outside ; so tha t infection does not occur across t he unbroken skin , and if occasionally by the mouth, then only by penetra tion of t he wall of the pha ryn x or after the virus has passed t he fi rst three stomachs. The transitional ep ithelium of th e conj unctiva is not a n effi cient barrier, a nd the stra tifi ed , cy lindrical epithelium of the t rue nasal mucous m embra ne is passed wi th ease. It is probable t hat t he v ir us ma kes th e passage of such epithelia within or attached to wandering leu cocytes. Sources of in fec tion a re con fined to th e bodies a nd fresh excre tions of animals a ctu ally sufferi ng from rin derpest . The possibility of tra nsmission of rinderpe t by blood -sucking fl ies h as been dem onstrated experimen tally, but much observation in the fi eld will be necessary before it ca n be stated wh et her at certain seasons such in sect s a re importan t tra nsmitters. In nature, t he commonest way in which th e disea se is c:; pread is probably by direct contact of t he n asal m ucous membra ne with infec tive excretions. ME CHANICAL MILKING .* By DR. GALLI A.
I N a n a rticle which I wro te under the above heading in the
Agricultural S cientific Paper for Czecho- lovakia (No. 11 of t he 10th April, 1925), I said t ha t I was n ot a t tha t time in a position to be able to express any defi nite opinion u pon the advantages or disadvantages of milking m achines, or , indeed, with regard t o the advisability of using m echanical milking a t all. If an y opinion is to be expressed about mechanical milking, it is absolutely n ecessary to make accura te compa rative test s between m ilk which has been drawn b y hand , a nd milk which has b een d rawn t hro ugh a m achine . Bact eria and m ould funguses have th e most active effect on milk . For t his reason th e ca re taken in drawing milk and storing it under t he most scrupulously clean conditions is of the utmost importa nce if th e milk is required to be kept for any length of time. * Abstract from Th e S cientific Agricultural P ap er. Czecho-Slovaki a.
356
The Veterinary Journal
Up to 100,000 bacteria per cubic centimetre is quite u sual in milk which h as heen drawn by hand. All th e changes which th e milk undergoes after it has left the udder are of bacterial origin . T r.erefore, to show how bacteria can be excluded from milk is of great practical importance to the milk producers and t o the ret ailer. In any case, it is of t he grea t est importance to have as few germs in the milk as is possible. Germs which enter the milk during t he process of milking come fro m the dry hairs of the udder and are shaken into the milk pail as the hand works on the t eat. Hay dust , small particles of foodstuffs, dirty milk vessels and especially the dirty h ands of milkers, consti tu te the principal sources from whence contamination arises. Very careful method s have to be adopted if milk with a low bacteriological content is to be produced . The actual constituents of milk are affected by the breed of the animals (each with their own peculiarity), the point in the period of lactation when the milk is drawn , the sexual activity, the food, exercise taken, the warmth and general comfort or otherwise of the cowsheds; but most particularly th e manner in which the actual milking is accomplish ed. As the period of lactation advan ces, the amount of fat to be found in the milk generally increases. The last milk drawn (known as the s trippings) is always richer in fa t than the first milk taken . F or this latter reason, only that milk which has been regularly milked right out to the last drop is known as " bes t milk " in the milk trade. It is clear, therefore, that a ttention must be paid to uninterrupted and complete milking out of the udder and consequently the solution of this problem is to be found in a machine which is absolutely precise and regular in its action . The quantity of milk drawn is also of the greatest importance. I t is only possihle to det ermine which method of milking is t he most productive by m aking an exact comparison of the amount of milk obtained b y each method. Such a comparison must he made throughout the whole of a lact ation p eriod, or at the least over several months, and then not only of milk obtain ed from one cow, but from a great number of cows, each in tl:e same period of its lact ation , or otherwise an increase or a decrease in milk yield can be attributed to other causes than that of the method employed of milking the cows. Hand milking is an unn atural proceeding. That is obvious and is impossible t o deny. If the sucking of the calf on the t eats is h eld to be the natural way of emptying the udder, then the process of hand milking is quite different and consequently must be unn atural.
Mechanical jl,lilking
357
Because the bulk of the milk is secreted by the cow during the actual process of milking and because she possesses the po\yer to stop this secretion if she is unsatisfied or otherwise dislikes the process of milking, therefore the amount of milk obtained depends principally upon the skill of the milker. The importance of the way in which the milking of a cow is done is proved by the numerous schools of thought which exist as to how, precisely, hand milking should be accomplished, and the courses at different colleges which are held to teach the theory and practice of milking. T aking into consideration the fact that each hand milker on a farm has of necessity to milk a number of cows, then it will be agreed that it is only the conscientioLlS milkers who will milk out completely every cow. When milking a number of cows, the hand milker is apt to get tired and consequently becomes careless and sloppy in his milking. For this reason the act of milking cannot be as pleasant for the cow as it really would be if she were milked in a natural way. Another result is that the quantity of milk obtained will be less than which is actnally possible. A milking m achine can be made which is absolutely uniform in its operation and soothing in its action. The factor of fatigue of the opera tor cannot affect the cow. Provided that the construction of the apparatus is based upon the act of sucking of the calf, which is the fu ndam ental and natural method of milking a cow, then a milking machine will be preferable to a hand-milker. I would observe that cows which have shown themselves t o be restless when hand milked very soon and easily become accustomed to a good milking machine. As regards the complet e milking dry of the animal it must be remembered that the lactic gland s are always secreting milk. This milk will collect in the milk cisterns, so that even if the milking has been very completely carried out, nevertheless, in a very short while after milking is over it will be possible to draw off further milk. It is true, th erefore, that theoretically a cow can never be milked right out . From experience, however , it can be shown that prolonged stripping of cows is not profitable. When stripping the cows is recommended after the machines have been taken off, it is done in order to ensure that a regular inspection of the teats is carried out. Nineteen cows in milk were selected and given index numbers in order t o carry out experiments for judging between both ways of milking. They were put on a farm at Blanda. Commencing on July 1st, 1925, samples of milk were tested in respect of their quality as well as quantity . The results are shown on the following table. From this Table it will be seen that from July 1st to September 27th
The Veterinary Jourl1al
358
t ests were made from hand drawn milk , and from September 28th t o 12th Octob er from machine drawn milk. During th e period of hand milking the following food was given ' A. Green food as much as the cow would eat. B. 2 Kgs. mixture of : 1 Kg. bran. t Kg. malt. 1 Kg. oil cakes. 11 Kg. barley meal. During the period of m achine milking the food consisted only of beetroot leaves (sugar refin eries), and a t night barley straw was m ixed with them . COMPARI SON BETW EEN H AND AND MACHI NE MI LK I NG OF 19 COWS . (a) By
H AND M ILK I NG .
Daily Record . Date
...
1/ 7
2/7
3/7
4/7
5 /7
6/7
7/ 7
8/7
9 /7
10 / 7
-- -- -- -- -- -- -- -- -Milk in Litres Fat Content %
163·0 163·0 160 ·5 169·0 159·5 165 · 5 158·5 158 · 0 158·5 157· 5
-- -- -- -- -- -- -- -- --
-- - -
-- -- -
- -- -- -- --
Maxim u m Variation in Fa t Co n tent % ... Date
...
14/7 15 /7 16/7 17 /7 20/7 27 /7 3 /8 10/ 8 -- -- -- -- -- -- -- -Milk in Li tres 150·0 143 ·5 146·0 14 1 · 5 143 ·5 140 · 0 127 ·5 124·5 ------ -- -- -- -- -- -- -- -Fat Conten t %
17/8
122·0 11 6·
--
-- -- -- -- -- -- -- -M ax i mum Variation in Fat Co n tent % ... Dat e
.. .
3 1/8
7/9
14/9
21/9
Average .
-- -- -Milk i n Litres
135·5 147· 5 156 · 0 149 ·5
- Fat Con tent %
148·2
-- -- -4 · 19
-- -- -- -- ---M ax imu m V ari atio n in Fa t Co n t ent. % ...
0- 27
24/8
--
Mechanical Milking (b) By
MACHINE MILKING .
Dail y Record . Date ...
...
. ..
28/9
29 /9
-- - -
Mi lk in Litres Fat Content
%
30/9
I JlO
-- -- -
2/ 10
-
3/ 10
4/10
-- -
-
5/10
6/10
-- --
... 163·0 162 ·5 159 · 5 163·5 156·0 155 · 0 159·0 162·5 157 · 5 - - -- -- -- - - -- - - - - --
.. .
-- -- -- -- -- -- -- -- -
Max imum Va ri ation in Fat Conten t %
...
... / 7/10 8JlO 9/ 10 10/ 10 11 / 10 12f10
Average .
Mi lk in Litres
... 157·0 152·5 152· 5 156·5 156 · 5 159·0 -- - - -- -- -... - - - - - - - - - -.. - - - -
164·8
Date ...
Fat Co ntent
%
Maxim um Vari ation in Fat Con t e nt %
4·28
0·14
A comparison of the tables gives the following r esults : 1.
In the first place the great inconsistency between different cows· milked by hand is striking. This influences of course the total quantities per day from the 19 experimental cows. On the other hand you will see from the table of machine drawn milk how very constant is the total quantity of milk taken from the cows. There art:: no great fluctuations. 2. It can be shown that at the commencement of the hand milking experimen ts one or m ore cows showed a certain maximum quantity which later in the experiment fluctuated or dropped. Directly , h owever, the machine milking was b egun the old high level was obtained which is a sign that by m achine milking all the milk which the glands produced was drawn. 3. During the period of hand milking the feed for the cows was in every way stronger than it was during the period of machine milking. N evertheless, you will notice that the total quantity of milk in the later case was greater than in the first case. From the three observations made above the following can be drawn : l.
2.
conc1usion~
With milking machines the milk gland is always working uniformly and is always uniformly emptied. The milk gland is absolutely emptied, I.e., secretes all the milk it possibly can.
The Veterinary Journal
.360
We a rrive at similar conclusions by comparing the fat content in hand-drawn milk and that in machin e-drawn milk. In fact , we can go further and show that the far content in hand-drawn milk is s ubject to greater fluctuations than that of machine-drawn milk. You will notice that the difference between the lowest and the highest quantity of milk from the different experimental cows is greater i n the case of hand-drawn milk than it is in the case of machine-drawn milk. The a mount of fat in machine-drawn milk is a little greater than it is in hand-drawn milk, although, as I have pointed out above, the food given to the cows during the period of hand milking was inferior to that which was given during the period of inachine milking. This astonishing result can be explained by the fact that with machine milking the udder is milked out a nd the last quantities of milk contain
" 5 6
:Bottle No. 1 2 3 4
5
Bottle No . 1 2 3 4,
" 5
Right Front T eat. 96 g. Milk 84g. 90 g. 80g. 98g. 45g.
Amount of F at . 3'3% 3'7% 4 ·0 % 4'1% 4· 4°/' ,0 5'7%
Left Front Teat. 90 g. Milk 88 g. 84g. 78 g. 44 g.
Amount of Fat. 3·2 % 3'3% 3'4% 4·2% 5·2 %
Right Rear Teat. 87 g. Milk 89 g.
Amount of Fat. 3·1% 4,0% 5'9% 5'9% 8'5%
100 g.
92 g. 39 g.
Mechanical M ilking Bottle No.1 2 3
4 "
[) (j
Left R ear Teat. 86 g. Milk 87 g. 85 g. 78 g. 88 g. 78 g.
361 Amount of Fat. 2'5 % 2'6 % 2·8 % 2·9 % 6'8% 9'5%,
Th e teats were milked ou t one after the oth er and not simul taneously. Adjacent quarters would b e affected by this method with the result that a small quantity of milk would collect in the milk cistern of a teat which had alread y b een milked. Th erefore, the t eats were re-milked at the end of tbe milking of all quarters, with the result that 74 grammes of milk were obtained out of the four teats, having a fa t content of 7·1 %. This shows that the milk collected in the milk cistern during the day and the first drawn off is the poorest. The fat content of milk increases during milking, and you can sec fro m the above tables that the fat con tent rises as the milking proceeds. When putting all the milk together, it is this high fat content a t the end of milking which corrects the low fa t content a t the commencement. If a cow is not milked out carefully, therdore, the m ean content of fat in the whole milk quantity will be lower than it need be. For example, if this last drawn milk had been disregarded, then the average content of fat for the single teats would h ave been3 · 85 % 3·77 % 4'03% 3'56% But by adding the last drawn milk the corresponding average fat content is raised to-4'03 % 3·95 % 4 '46 % 4'49% and the average fat content for all four t eats t ogether would beWithout last drawn milk 3·83 % With " 4·24°/" It will be seen from the ahove that the fat content in milk is very dependent upon th e way in which the cow is milked. It is quite easy, therefore, to appreciate the common idea that results of milking vary in direc t proportion to the conscientiousn ess of the hand milker.
362
The Veterinary Journal
Because the fat content in machine drawn milk is higher than the fat content in hand drawn milk , it follows that the udder is better emptied in the former case. The chief quality required of commercial milk is tha t it shall keep sweet as long as possible. This is governed by the number of bacteria which enter the milk during the process of milking and s ubsequently. The b acteria which enter the milk do 110t commence their destructive action until after a defi nite period of incubation. The period of incubation in warm milk is from 38 hours and in milk cooled down ab out 10 degrees, it is bptween 52 and 75 hours. The precise time is dependent upon the number of bacteria present . It will be seen, therefore, that clean milk has an incuba tion period of about one to four times longer than dirty milk. Milk hygienically produced t akes double the time to curd tha n contaminated milk takes. In order t o compare hand milking with machine milking in so far as contamination of the milk was concerned , counts were taken of samples. Samples were taken once weekly of hand drawn milk and twice weekly of machine drawn milk. A furth er daily sample was taken to watch the results of the cleaning of the machines. B acteria colonies were counted, bred on OrIa-Jensen nutritive substratum, dilution 1-1 ,000. The counts of hand drawn milk were : -136 ' 000,152 ' 000,193'000 , 117'000, 149'000, 187'000, 158 '000, 126 ' 000, 134' 000, 172·000. The counts of machine drawn milk were : -11·000, 23 ' 000, 19 ' 000 , 28 '000, 35 '000, 33 ' 000, 41 ' 000. After the .first cleaning which has to b e repeated every week , the numbers of bacteria were 21 ·000, 26'00;), 24 ' 000, 31·000, 36'000 , 29·000, 34 ·000. There is no doubt. b ut that these counts could h ave heen reduced considerably by more careful cleaning of the teats and of the milking machine. The variou kinds of bacteria found in milk have different reactions on the milk. For instance, bacilli, acidi lactiti , bacterium coli, etc., ferment the milk and tum it into lactic acid, which in turn under certain conditions turns the casein into curds. Further experiments were carried out to discover whether machine milking excluded any particular kind of bacteria or whether milk drawn by a machine contained larger quantities of any particular bacillus than did milk drawn by hand. For convenience of comparison the milk was gr aded into four classes according to the time taken to bring about decolorisation. When any impurities such as food or particles of dirt were found in the milk, then it was classified one grade lower. .
Mechanical Milking
363
The results of hand drawn milk from 30 samples were : Grade I .. Nil. II 3 samples. III 18 IV 7 2 V The result of machine drawn milk from 21 samples wereGrade I 19 samples. II 2 These results are very favourable to mechanical milking and are obvious when you consider that mach ine-drawn milk never comes into contact with the air in the cowshed s. Further, the only impurities which can enter the milk are bacteria on the teats in the udder or on different parts of the machine. R eviewing the profits and working costs, the following data were s upplied to me by the Directors of the Mueglitzer Sugar Refinery. When hand milking was done the following staff were required at Blanda Farm :1 Head Cowman at K c. 22 per day = Kc. 22 6 H and Milkers Kc. 18 = Kc. 108 2 Assistants = Kc. 36 " Kc. 18 Total 9 Kc.16 6 Representing a Wage Sheet of Kc . 4,980 per month. Since the introduction of mechanical milking the following staff only are n ecessary:1 H ead Cowman at Kc. 22 per day = K c. 22 1 Second Cowman" Kc. 22 = Kc. 22' 3 Assistants " Kc. 18 = Kc. 54 Kc.98 Total 5 Representing a Wage Sheet of Kc. 2,940 per month . . To this last figure must be added the cost of power to drive the p lant, which for this particular farm was Kc. 650 per month . Total costs are therefore :. By Hand Milking Kc. 4,980 per month. " Mechanical Milking Kc.3,590 Saving Kc. 1,390 In addition , the increase both in quantity and quality of milk obtained, when mechanical milking is done, must be taken into consideration, and it will be seen what a good investment the plant reallv is.
364
The Veterinary Journal
Summarising the results obtained with the milking plant described above in * this journal, the following conclusions are reached. 1. The quantity and quality of the milk p roduced both show an improvement and a t the same time increased profits are obtained due to lowering of labour charges. 2. Milking with this plant is not injurious to the mammary glands, but is actually beneficial : t he unnatural action of h and milking is done away with and in its place a na t ural action is substituted very simila r to the sucking of t he teats by a calf. The milking is always uniform and eliminates the personal elements of inexperience, temper, etc., which occur with hand milking. 3. F inally, from a hygienic poin t of view, mechanical milking is ideal as contamination of the milk in the shed becom es p ractically impossible. I wish to express my very best thanks to Mr. Oskar Kunovsky, Professor in Chemi stry of the St aats-R ealgymnasium in Hohenstadt , for his extremely valuable support in this work ann especially for the carrying ou t of all the chemical t ests men tioned .
NOTES F ROM THE DISSECTING R OOM. By A . W. W HI TEH OUSE, M.A., M. R.C.V .S., Principal and Professor of Anatomy, The Veterinary College, Gla sgow .
SURGICAL R OADS TO THE P ARAPHARYNGEAL LYMPH GLANDS AND THE GUTTURAL POUCH IN THE H ORSE. TOGETHER with Captain H . S. Eakins, Veterina ry Corps, U.S.A., I reported (about 1!H 4) in wha t was then the .-\merican Veterina ry R eview, on a compara tively safe and very easy method of reaching these structures, and I have sin ce tanght this route to my studen ts in anat omy; but as very little notice seems to have been taken of our work , I take this oppor t unity of goi ng over t he ground again. Guttural POllch d isease must be very rare: I have seen one clinical case, which I always suspected to have been caused by opera tion, and in th e hundreds of dissections th a t I have looked at I have only found one diseased pouch, tha t bei ng an ex tension downwards from an old poll-evil of t he indura tive type. On the contrary, paraphary ngeal abscess is p retty common in strangles and th e sym ptoms are often alarming.
* Th e m il ki ng machi ne described i n the above abstract was the AlfaLaval Mi lk cr.- EDITOR ,. VETER I NARY J OURNAL ."