Part 3 (1/2)

[Illustration: FIG 10 Sanitary ned to diminish the introduction of hairs, scales, dirt, etc, into10) and found that 63 per cent of the dirt and 29 per cent of the bacteria were prevented froerainst 43200 per cc in a common open pail This milk did not sour until it was 64 hours old in the first case while in the latter it curdled in 43 hours

~Air in barn~ The at is done may frequently contribute considerable infection Germ life is incapable of developanis which contributes to the production of dust in the stable and aids in the stirring up of the saanis of dry fodder and the bedding of ani in the air Dust in Fraser found the dust frohth as erm life as that from hay or bran[36] In time most of these dust particles settle to the floor, but where the herd is kept in the barn, the constant movement of the animals keeps these particles ht to lessen the ger dry feed should not be done until after [37] In some of the better sanitary dairies, it is custoed with special reference to the elimination of all dust In this way this source of infection may be quite obviated as the air of a clean, still room is relatively free from bacteria, especially if the floor is moistened It has often been noted that the milk of stall-fed animals does not keep as well as that milked out of doors, a condition in part attributable to the lessened contamination

[Illustration: FIG 11 Effect of contaminated air The number of spots indicate the colonies that have developed from the bacteria which fell in 30 seconds on the surface of the gelatin plate (3 inches in diameter) This exposure was made at time the coere fed]

~Relative importance of different sources of infection~ It is impossible to measure accurately the influence of the different sources of infection as these are continually subject to eneral rule, however, where milk is drawn and handled without any special care, the utensils and the anier proportion of dirt and bacteria that find their way into ned to exclude the largest nu in the foreinto practice the various suggestions that have beenthe bacterial content of anisms found therein, and at the sa quality of the erm life in inal nu He reports a series of experied less than 10,000 bacteria per cc, while that secured under ordinary conditions averaged over 500,000

[Illustration: FIG 12 Bacterial content of rowing on gelatin plate Co 13, where sa culture

Over 15,000 bacteria per cc in this ives an illustration as to what care in12 shows a gelatin plate seeded with the sa the culture indicated by Fig 13 The first plate was inoculated with erm content of which was found to be 15,500 bacteria per cc, while the sample secured under as nearly aseptic conditions as possible (Fig 13) contained only 330 organisms in the same volume

[Illustration: FIG 13 Bacterial content of erm content is shown by smaller number of colonies (330 bacteria per cc) Co 12]

~”Sanitary” or ”certified” enerally introduced into rade erm content as much as possible Milk of this character is frequently known as ”sanitary,” ”hygienic” or ”certified,” the last ter used in connection with a certification from veterinary authorities or boards of health as to the freedoious disease

Frequently a numerical bacterial standard is exacted as a pre-requisite to the reco physicians Thus, the Pediatric Society of Philadelphia requires all children's milk that receives its recommendation to have not more than 10,000 bacteria per cc Such a standard has its value in the scrupulous cleanliness that must prevail in order to secure these results This in itself is practically a guarantee of the absence of those bacteria liable to produce trouble in children The nuly lohen compared with ordinary milk Naturally, there is considerable fluctuation froerure without any apparent reason The average results though, show a greatly reduced nuton dairy in 113 exae of 6,485 bacteria per cc The daily analyses made of the Walker-Gordon supply sold in Philadelphia for an entire year, showed that the milk almost always contained less than 5,000 bacteria per cc and on 120 days out of the year the geranisms per cc or less

From a practical point of view, the improvement in quality of sanitary milk, in comparison with the ordinary product is seen in the enhanced keeping quality During the Paris Exposition in 1900, milk and cream from several such dairies in the United States were shi+pped to Paris, arriving in good condition after 15 to 18 days transit When milk has been handled in such a way, it is evident that it is much better suited to serve as a food supply than where it has undergone the feres incident to the develop precautions to all es that it is necessary to protect it froinal purity is to be maintained, and yet, from a practical point of view, the use to which it is destined hasThe effect of the bacterial contaely upon the way in which the product is used To the ed in the distribution of milk for direct consumption, all bacterial life is more or less of a detriment, while to the butter-maker and cheese-maker some forms are a direct necessity It is unnecessary and i milk destined to be worked up into factory products as is done, for instance, in sanitary milk supplies, but this fact should not be interpreted to mean that the care of milk for factories is a matter of small consequence In fact no more important dairy problem exists, and the purer and better the quality of the raw material the better the product will be Particularly is this true with reference to cheese-

Dairymen have learned many lessons in the severe school of experience, but it is earnestly to be hoped that future conditions will not be summed up in the words of the eminent German dairy scientist, Prof

Fleischmann, when he says that ”all the results of scientific investigation which have found such great practical application in the treatment of disease, in disinfection, and in the preservation of various products, are al”

~Growth of bacteria in milk~ Milk is so well suited as a ht be expected that all anisms would develop rapidly therein, and yet, as a h the milk may be richly seeded At ordinary temperatures, such as 70 F, no appreciable increase is to be noted for a period of 6-9 hours; at lower teed to 30-40 hours or even longer After this period has elapsed, active growth begins and continues

The cause of this suspended developermicidal properties inherent to the milk[40]

Milk is of course seeded with a considerable variety of organis and inert species are thesparsely, if at all As ins to occur More or less developain the ascendency, owing to their being better suited to this environment; they soon outstrip all other species, with the result that norrowth of this type is largely conditioned by the presence of the ar is reoes putrefactive changes due to the fact that the putrefactive bacteria are able to grow if no acid is produced

~Relation of tein in milk, the temperature at which it is stored exerts the most profound effect on the rate of development When milk is not artificially cooled, it retains its heat for some hours, and consequently the conditions become very favorable for the rapid anis results obtained by Freudenreich[41]:

_No of bacteria per cc in milk kept at different te 10,000 30,000 8 ” ” ” 25,000 12,000,000 12 ” ” ” 46,000 35,280,000 26 ” ” ” 5,700,000 50,000,000

[Illustration: FIG 14 Effect of cooling rowth of bacteria]

Conn[42] is inclined to regard te quality than the original infection of the milk itself Milk which curdled in 18 hours at 98 F, did not curdle in 48 hours at 70, and often did not change in teeks, if the temperature was kept at 50 F

Where kept for a considerable period at this low temperature, the milk becomes filled with bacteria of the undesirable putrefactive type, the lactic group being unable to for ater can be used for cooling, if it is possible to secure it at a teives better results, and in sureatly to be desired The influence of these lowered te distances[43] by rail for city supplies, if the teht andmilk~ Not infrequently it happens when old milk is es is more rapid than would have been the case if the two htes in both The explanation for this often irowth one on in the cooled milk, and when this material is added to the warmer, but bacteria-poor, fresh milk, the temperature of the whole rowth of all bacteria than would have occurred if the older milk had been kept chilled

~Nuanisinal ae of the milk, and (3) the temperature at which it has been held These factors all fluctuate greatly in different cases; consequently, the gerly wide variations Here in America, milk reaches the consuh it ely to thethe milk _en route_ to market Examinations have been wick and Batchelder found in 57 tests of Boston milk from 30,000-4,220,000 per cc Jordan and Heinee from 100,000 to 1,000,000 while nearly one half were froerm content of city milks increase rapidly in the suanisms per cc in winter, about 1,000,000 in cool weather and 5,000,000 per cc in hot summer weather Knox and Bassett in Balti and nearly 4,500,000 in summer Eckles[45] studied milk under factory conditions He finds from 1,000,000 to 5,000,000 per cc in winter, and in summer from 15-30 millions