TO ELIMINATE TUBERCULOSIS.

Dominion, Volume 2, Issue 477, 8 April 1909, Page 5

TO ELIMINATE TUBERCULOSIS.

AN EFFECTIVE METHOD. GOOD BEGINNING FOR CLEAN HERDS. A good outline of a practical, inexpensive way of eliminating tuberculosis from a herd of cattlo was given recently by a European investigator in tho "British Veterinary .Record." This authority in ten years changed'a largo Danish herd, in which oyer 80 per cent, of the animals were tuberculous, into a herd of completely healthy animals. Ho did this without any sacrifices of the diseased animals. His method was to isolate the few animals which were healthy and use only their milk for rearing the calves. As each of these calves, noarly all of which grew up free from disease, came into profil, on© of the tuberculous cows was sold to the butcher. As this plan is one that may appeal to some Now Zealand dairy farmers, fuller particulars of the process will be worth publishing. In this somewhat unattractive subject— tuberculosis in dairy herds —there is one bright spot that seems to illumine the whole question with encouragement. It is the fact, pointed out by the Danish authority, that oyer 99 per cent, of all the calves born_ are free from disease. • Even if they come from a diseased mother and father, they do not inherit the disease. ' Each calf born, theretore, is fair material for building up a healthy member of tho herd of the future. Tho calves are free, from tuberculosis so long as they do not come into contact with infection after birth. Practically, the only calves that are born tuberculous are those which come of a mother which bears advanced external signs of the disease. The importance of this fact is great, for it enables the purification of a herd to proceed without any loss to the owner—without any cost except that involved in the maintenance of the herd in two separate portions. Shch a system.as that adopted in the Danish test, is calculated to' inspire tho owner with confidence and some enthusiasm; -he feels that it is ■; safe to set about finding out his cows, and that his.welfare no longer depends 1 on his success in concealing whatever cases'of the. disease which his herd may contain. ■ Unfortunatsly, the law in New Zealand is not constructed on these lines. If a dairy farmer has his herd tested with tuberculin, it is understood'that he.is compelled to'permit the reacting animals to be slaughtered. For all one knows to ■ tho contrary, such a law may therefore be calculated to defeat the purpose for which it'exists. Farmers are not encouraged to submit their herds to the test. Let us follow up-tho stages of the Danish experiment. It was performed in, a herd of 208 cows. Of the entire herd of cows, heifers, and-steers, 80 per cent, reacted to the tuberculin test. The 20 per cont. of. healthy animals were separated froSji the others, although the farm and buildings were not well fsuited - for isolation;, and the and diseased sectio.ns of the herd were attended by separate staffs, such as would be the case if the farmer himself milked the healthy cow and left the more numerous less healthy ones to his men. They grazed in separate paddocks, and the healthy cows were, of course, never put into pastures which had iust previously boon grazed by the rest of the herd. The housing accommodation was divided into two parts by a wall—weferably of brick—and the absence of any door in this still further reduced the liability i\o infection. . ■ \ One factor that caused the experimenter in the Danish case no little anxiety was the knowledge that, in the supposed healthy part of the herd, there might still be ono or more affected animals which had not been revealed; by,-the tuberculin test, and which therefore could contaminate the others in the section and wreck the whole of the work. To lessen this danger as far as possible, the tubercijlin test was repeated.on the healthy section' s every six months;" !' Meanwhile,, the less healthy section of the herd—the 80 per cent, which were tuberculous from the firstswere allowed to live, breed, and supply milk so long as they appeared externally to be healthy. Thus, although the selling of niilk from ..cows known to have reacted might appear objectionable, ; yet the . milk was no worse) than it ,was before the test was made. Tho one thing important was to be careful that .the unhealthy cows did not infect the healthy cows. This, hitherto impossible, was noWjComparatively a simple matter. The rearing of the calves, on which the future clean herd was to be built up, was the most interesting part of tho operations. When a tuberculous cow calved, the calf was removed and fed either on sterilised milk or on the'milk of the healthy cows. At first when sterilised milk was given to newly-born calves they suffered. But if the mother's colostrum was fed for one day, the calf imbibed Sterilised milk afterwards without injury.: But for complete safeguard the colostrum and milk from tho healthy cows were-relied on. The speed; with which this ultra'-diseased herd was purified is shown in the following figures, representing the numbers reacting. At first in 1892 there were 131 cows which reacted, and 77 which were recorded as healthy. The diseased aaimaJs, though.retained, wore not re-tested, but the healthy section was re-tested periodically. Th£';results on them were as follow:— - JI?J- Cows Tested. Reacted. ■.•■m\) 227 44 " - 1902 244 - none — 1903 ... :.. 246 none.. ■'I-There are numerous circumstances which found to discourage farmers from .adopting these methods generally. One was fthe unavoidable slowness of the progress "made. The maintenance of the herd in two separate sections entails extra labour, and owners were sometimes tempted to 'relax their efforts and spoil the whole undertaking, especially when they found that on a second test a number of animals reacted which originally had passed the test. This- point needs to bo clearly explained to the owners beforehand. The labour involved in running two separate herds is not noticeablo if the owner happens to occupy two farms, for in that case the healthy animals may bo kept on ono and tho reacters on tho other. The danger of infection would also be lessened.