TUBERCULOSIS AND THE CALF

Dominion, Volume 7, Issue 1969, 28 January 1914, Page 10

TUBERCULOSIS AND THE CALF

SOME BRITISH EXPERIMENTS. HEALTHY "CALVES FROM AFFECTED COWS. Tho British Royal Agricultural Society has been for threo years carrying .out a series of tests to demonstrate ■that by isolation it is possiblo to rear Jiealthy stock from tuberculous parents. The report of tho result of those experiments has just becomo available. The place selected for the tests was a farm near Woburn, which was placed at the disposal of tho committeo in tho -autumn of 1910. The buildings intended for tho reception of tlid young wive a wero provided with a, new impervious concrete floor, with surface drainago, the object being to render cleansing, and disinfection easy. Tho floor spaco divided up by wooden sparred, partitions into pens of a .sizo suitable for calves. Two buildings of this description woro made available, these being 'separated by a smaller shed,: which contained a largo open copper for heating tho milk, and providing tho boiling wator for washing and scalding tho milk-vessels and feeding-pails. I Arrangements were' made with several .owners to allow their cows to be submitted to- tho _ tuberculin tost, and to [placo at tho disposal of the committeo jany selected' as being suitable untilafter they had calved. As soon as possiblo after tho test .had been carried tho. selected reacting cows were (sent to tho "society's experimental "form at "Woburn, and kept .thero until. they, .(had calved and cleansed, after' which .■they wore returned to their owners. , Tho only real difficulty in the demonstration aroso from tho risk that tie calves might becoirio'. infected after ■ birtn, and tho. problem- was to prevent the access of tubercle bacilli to them.'ln '.nature thoso bacilli como from one source !(viz animals or human beings affected (with tuberculosis), and, as regards .the jbacilli which cause the disease in cattle,; .tho human source mav for all practical purposes -bo; left out;'of account. The jarrangemerits' had, therefore, to aim at ;iiisfcihg it 'impossible for tubercle bacilli '.to reach tho calves either directly or in?dircctly from tuberculous animals, and especially from animals, of their own species. Tho'most immediate risk obviously Wa3 that tho calf might become linfected from its mother To guard jagaiiist this,-each cow at tho timo of calving was tied up,'and as soon as the '.calf was;borh'Jt was carried.into a buildling that had not previously been ÜBed for cattle, where it'was rubbed-dry. As ■soon as possiblo thereafter it was • removed by cart to the calf-rearing premises, a mile distant. Further, a man in oharge of the calves was kept entirely for this work, and !had no contact with •other cattle.'

, As the calf houses here had been to Ti large extent .reconstructed, provided jwith. a new floor, cleansed, disinfected, 'and whitewashed, it was permissible to assume thatthero \vas little or no risk that tho calves could ' hecomo infected by bacilli remaining over from the pre'vious tenancy. The milk on which tho calves were 'fed vas obtained from a. farm in tho neighbourhood, and before use it was raised to n temperature of not less than 100 des. Fahr. by immersing tho vessels containing it in water which was kept boiling in the copper. Assurance was thus obtained that any bacilli which might have Keen brought from the cows at the neighbouring farm had been killed.

AVhori milk diet was stopped the calves were kept on two fields which were reserved :exclusively. for their .use, end they were nover allowed to come into contact with other animals with the oxceptiou of the bull, which was put with' them to servo the heifers'ln Sopteriiljer, 1912. This bull had passed the tuberculin test before he was brought to the place, 'and, after arrival, he was again tested, witii tho same result.

Inasmuch ns no evidence of tuberculosis was found in any of tho animals after they weep slauehtored, these experiments may be held to have demonstrated "that-by means'of isolation'it is possible to rear healthy stock from tuberculosis parents."

It is trim that this involves the assumption that a distinct, .reaction to tuberculin may in practice ho accepted las proof that tho reacting animals are /tuberculous, for tho cows which save I birth to the calves were not submitted jtq post-mortem examination. To furinish absolute proof that the cows were /tuberculous was not considered necesisaiTj and to have done so would have [added greatly to the cost of tho demonjstration. It may bo pointed out, however, that if thero are any breeds who consider the tuberculin test unreliable, the experiments, nevertheless, have considerable value for them,.since they jrjrove. that by raonas of isolation it is

possible to rear non-reacting calres from reacting cows. Although the experiments assumed and were not intend-ed-to prove, tho reliability of the tuborculin test when properly carried out, they do add further testimony to its value. For, on tho assumption that the test is, quite untrustworthy, there does not appear to bo any reasonable explanation of the.fact that, with one excoption, none of the calves reacted, whjlo among 116 apparently healthy cows 32 (or 27 per cent.) reacted distinctly. Tho. case of tho calf referred to illustrates one- of tho sources of error in testing animals % with tuberculin. The facts set forth in this animal's record indicate that it suffered from some temporary illness, of which tho cause was not determined, and that this illness was resopnsible for tho rise- of temporature, after the injection of tuberculin.