Testing of Dairy Cattle for Tuberculosis

New Zealand Journal of Agriculture, Volume 84, Issue 3, 15 March 1952, Page 163

Testing of Dairy Cattle for Tuberculosis

THE compulsory testing for tuberculosis of dairy herds on town milk supply farms has now been in operation about a year. Up to the end of January this year 57,952 dairy cattle have been tested and 3826 reactors found, a

percentage of 6.6 of affected cattle.

Many of the reactors did not show extensive disease lesions, but as eradication is the ultimate objective of the scheme, all reactors, irrespective of the extent of the disease, have been removed from herds and destroyed and their owners compensated. In some areas of dense cow population the percentage of reactors is high and has in fact exceeded our original expectations. In spite of this and the consequent higher cost of compensation, the Government’s plan to complete the testing within the planned 3 years will be carried out. Priority to Herds Supplying Raw Milk In the testing programme priority has so far been given to the testing of herds supplying raw milk. There has been considerable expansion in milk treatment stations and about 85 per cent, of all town milk sold in urban areas is pasteurised. It has been known for some years that incidence of tuberculosis disease in cattle varies considerably from district to district and from farm to farm. In the South Island testing the average of reactors has so far been 2 per cent., but in the North Island the average is between 9 and 10 per cent. Details of Testing Details of the tuberculosis testing of dairy herds supplying raw milk to the principal centres of population are as follows: Cattle tested Reactors Per cent. Auckland . . . . 6918 614 8.9 Balclutha . . . . 1074 10 0.9 Blenheim . . .. . 965 10 1.0 .Christchurch . . 4929 179 3.6 Dunedin . . . . 8266 524 6.3 Gisborne . . . . 1328 70 5.3 Hamilton . . . . 1184 208 17.6 Invercargill . . 2726 26 1.0 Masterton . . . . 1994 37 1.9 Nelson . . . . 1282 2 0.2 Oamaru . . . . 1169 25 2.1 Palmerston North . . 3688 393 10.6' Pukekohe .. . . 667 79 11.8 Rotorua . . . . 595 61 10.2 Stratford ' . . . . 1620 102 6.3 Thames . . . . 604 92 15.2 Timaru . . . . 2701 65 2.4 Waimate . . . . 508 5 1.0 Wairoa . . . . 804 21 2.6 Wanganui .. .. 1129 114 10.1 Wellington . . 5881 450 7.7 Whangarei . . 549 9 1.6

Departmental experience shows that the disease is more common in low-lying, flat country and is aggravated if the area is subject to periodic flooding. On drier, better drained country a lower incidence of reactors can be expected. Once the difficulties which hampered early negotiations with town supply authorities were satisfactorily overcome the testing scheme has operated steadily with the resources available, and progress to date can be considered. good. Though the ultimate aim of complete testing of all town supply herds and destruction of all reactors has never been allowed to be clouded by other issues, at the same time adequate supplies of milk to urban areas have had to be ensured and application of the scheme in particular areas has been adjusted accordingly. Overseas Experience Great importance is attached to testing for tuberculosis in dairy cattle in some overseas countries. In Denmark, where because of war and post-war feed shortages herds had to be drastically reduced, reactors to the tuberculosis test formed the bulk of the animals culled for slaughter and, making a virtue of necessity, the Danes were able to establish tuberculosis-free herds on a national basis. In Canada an effective compulsory testing scheme operates and in U.S.A., where testing has been compulsory for 35 years, incidence of reactors has been reduced to less than l/ 2 per cent. Apart from a natural desire to have disease-free herds the rule in New Zealand, we might some 1 day have to face a trade disadvantage with our dairy products on a buyers’ market if our incidence of disease in dairy cattle could not stand comparison with that in the herds of our competitors. Testing of Factory Supply Herds A scheme for the introduction of tuberculosis testing for factory supply herds was recently presented to me by the Veterinary Services Council, which had had the prior approval of the New Zealand Dairy Board to its suggestions. A quick examination of the scheme, which is intended to be voluntary at first and then merges into compulsion, reveals advantages, some of which are closely related to the maintenance of disease-free town supply herds, which draw their replacements largely from factory supply herds. I am interested in the proposal as a forward step to the benefit of the dairy industry and the community generally, and have asked that it be examined by departmental officers to see what its introduction would involve in finances and manpower.

K. J. HOLYOAKE,

Minister of Agriculture.