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animals. What has been said shows without doubt that the loss of the whole or any considerable part of the by-products would make a very appreciable difference in a year's operation at any good-sized abattoir.

It would seem, if for no other reason than the saving of these byproducts, that concentration in slaughtering and competent inspection should be advocated and upheld from a commercial point of view.

PUBLIC EFFORT NECESSARY FOR REFORM.

Since the Federal law will not permit meat slaughtered under the insanitary conditions herein mentioned to enter into interstate and foreign trade, nothing remains but for it to be consumed within the State; it is therefore necessary for public opinion and effort to bring about a more cleanly and healthful condition in this direction. Let organizations having similar objects in view as this bring before the people the revolting conditions under which some of our meat is supplied and public sentiment will soon force those in authority to take measures to better these conditions.

This question of an adequate State inspection of meat was emphasized by Miss Alice Lakey, chairman of the food committee of the National Consumers' League, in an address delivered at the Jamestown Exposition July 19, 1907, in connection with the eleventh annual convention of the Association of State and National Food and Dairy Departments. Miss Lakey said, in part:

Will not this body of State and National officials use its influence to help in prevention by securing State inspection of cattle, slaughterhouses, and meat? Why are so many consumers acceding to the demands of the meat trust by paying increased prices for meat? Because such meat bears the stamp of the Federal inspector and the consumer has been educated by the public press to believe that such meat is safe. Many consumers refuse all meat not so labeled. Can not the States give consumers a label on State meat that shall be equally reassuring?

It is only fair to say, in conclusion, that a packer who submits to Federal inspection and destroys all animals that are unfit for food purposes incurs a heavy expense not known to the slaughterer who has no inspection of any kind and who sells diseased meat at the same price that he receives for healthy meat. Consequently the packer or slaughterer whose product is subjected to a rigorous inspection should receive, in all fairness, a higher price for his product than the packer or slaughterer who operates without inspection.

THE ECONOMIC IMPORTANCE OF TUBERCULOSIS OF

FOOD-PRODUCING ANIMALS."

By A. D. MELVIN, D. V. S.,

Chief of the Bureau of Animal Industry.

INTRODUCTORY.

It is the purpose of this paper to call attention briefly to the serious injury which tuberculosis causes to the live-stock industry from the economic standpoint and to suggest means of overcoming it, discussing the subject as it affects the United States. Regardless of the question of the communicability of tuberculosis from animals to man and the bearing of animal tuberculosis on the public health, it is a well-known fact that this disease causes heavy financial loss to the live-stock industry; and while the saving of human life affords the highest motive for combating tuberculosis, the prevention of financial loss is alone a sufficient reason for undertaking the eradication of the disease from our farm animals.

The movement in the last few years for a more wholesome food supply has resulted in drawing attention to the part played by tuberculosis as regards both health and economics. It must be realized that the exclusion of tuberculous meat and dairy products from the food supply means an appreciable reduction in the quantity of available food, with a corresponding tendency to an increase in the cost of necessaries of life. The economic problem therefore concerns not only the stock raiser and the producer, but the consumer, which means practically everybody. No nation is so wealthy that it can afford to sacrifice year after year a considerable and increasing proportion of its food supply, especially when by proper means the loss can be reduced and in time prevented entirely. This is a problem which must be faced eventually, and the earlier this is understood the more easily it can be solved.

THE PREVALENCE OF ANIMAL TUBERCULOSIS.

While tuberculosis among animals is less prevalent in the United States than in some other countries, it has progressed to an alarming extent even in this country, and is undoubtedly on the increase, especially in States where no adequate measures have been taken against it. The animals principally affected are cattle and hogs. The disease readily spreads among cattle that come in close contact. with each other, as in dairy herds, and experiments by the Bureau of Animal Industry have shown that it is easily communicated from

This paper was read before the International Congress on Tuberculosis at Washington, D. C., September 29, 1908.

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cattle to hogs by the common practices of giving skim milk to hogs and allowing them to feed on the excrement of cattle. The increase of tuberculosis among hogs in the United States has been very marked in recent years. Sheep and goats are rarely affected, probably because of a natural tendency toward immunity or because they are not generally exposed to infection.

The two principal sources of data as to the prevalence of tuberculosis among live stock are (1) meat-inspection statistics and (2) records of the tuberculin test. Meat inspection throws light on the disease in cattle, hogs, sheep, and goats, while the information derived from the tuberculin test is practically confined to cattle.

MEAT-INSPECTION STATISTICS.

The Federal meat inspection, as extended under the law of June 30, 1906, now covers more than half of all the animals slaughtered for food in the United States, and the proportion of animals found affected with tuberculosis under this inspection service affords a basis for forming some idea of the extent to which the disease exists among the meat animals of the country.

The following table shows the number of animals of each kind slaughtered under Government inspection during the fiscal year ending June 30, 1908, and the number and percentage found affected with tuberculosis.

Animals slaughtered under Federal inspection in the United States, with number and percentage found tuberculous, during fiscal year 1908.

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Even a larger proportion of the animals slaughtered at establishments without Federal inspection are tuberculous, as one effect of a rigid inspection is to cause the establishments under inspection to exercise care in buying animals so as to minimize condemnations, while suspicious-looking animals are naturally diverted to the small local abattoirs that have no inspection. This was demonstrated by comparing results at establishments soon after they were placed under inspection by the new law with those at establishments where inspection had been in force for a long time, relatively twice as many cattle being condemned for tuberculosis at the former as at the latter places. Taking these facts into consideration, it seems likely that more than 1 per cent of the beef cattle in the United States are affected with

tuberculosis to some degree, while over 2 per cent of the hogs slaughtered are affected.

THE TUBERCULIN TEST.

It is known that dairy cattle are more generally affected than beef cattle, as the tuberculin test has shown that from 5 to 25 per cent of the cows supplying milk to certain cities were tuberculous. For instance, tests made in 1907 on a large proportion of the herds supplying milk to the city of Washington showed about 17 per cent of the cattle reacting.

For fifteen years the Bureau of Animal Industry has been preparing tuberculin and supplying it to State and city authorities for official use, besides using it in tests by its own employees. Recently the reports of tests made with this tuberculin during this period have been carefully analyzed and tabulated. Out of 400,000 cattle tested there were 37,000 reactions, or 9.25 per cent.

The majority of the cattle tested were dairy cattle, and the tests were made under various conditions. By far the larger proportion of the tests were made on cattle that had been within a State for a year or more. In some cases tests were made compulsorily on all cows supplying milk to a city; in other cases they were made when requested by owners, and in still others when the presence of tuberculosis was suspected in certain herds. It is impossible to determine accurately the weight of all these factors; but considering the fact that while dairy cattle largely predominated their average is reduced by a certain proportion of other cattle, and offsetting against this the fact that the testing of herds under suspicion tends to raise the average somewhat, it seems reasonable to conclude from these tests that at least 10 per cent of the dairy cattle in the country are affected with tuberculosis."

A remarkable feature of the reports referred to is the manner in which the diagnosis by the tuberculin test was confirmed by postmortem examination on reacting animals that were slaughtered. Out of 24,784 reacting animals slaughtered, lesions of tuberculosis were found in 24,387, a percentage of 98.39. The Bureau has positive knowledge that in at least one State the testing was not done in a careful and reliable manner. If we discard the returns from this State, the proportion of cases in which the tuberculin reaction was confirmed by post-mortem is raised to 98.81 per cent. It is possible, too, that in some of the negative cases tuberculosis was really present, but the lesions were so slight as to escape detection on post-mortem examination by ordinary methods. Surely these figures, representing the work of scores of individuals in all parts of the United States

"Schroeder, in another paper in this volume (p. 148), estimates that not less than 20 per cent of the dairy cows are tuberculous.

over a period of fifteen years, bear strong testimony to the marvelous accuracy of the tuberculin test. Further evidence on this point is afforded by the slaughter, during the past year or two, in or near the city of Washington, of 126 cattle which had reacted to the test when applied by Bureau veterinarians, with only one failure to find lesions of tuberculosis on post-mortem examination, the percentage of accuracy being 99.21.

Properly prepared tuberculin applied by competent persons is thus shown to be a wonderfully reliable agent for diagnosing tuberculosis. In cases where the test appears to give unsatisfactory results this is usually due to the use of a poor quality of tuberculin or to ignorance or carelessness in applying it.

The following table shows the result of the tests above referred to, arranged according to States:

Results of tuberculin tests of cattle by State and Federal officers with tuberculin prepared by the Bureau of Animal Industry, 1893 to July 31, 1908, inclusive.

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