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This article was published in 1975
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An Outbreak of Tuberculosis at Canowindra, 1973.
C.H.R. Dent, M.V.Sc., Veterinary Inspector, Carcoar
In late November, 1973, 110 x 6-8 months old Tamworth porkers were consigned for slaughter at Cowra Abattoirs, from a Canowindra property. After slaughter, 16 total condemnations and 45 head and other condemnations were recorded for suspected T.B.
Quarantine was instituted immediately on this property (AES), and in December, 1973 a further 75 porkers of the same age were consigned for slaughter at Blayney Abattoirs, where 6 total condemnations and 31 head and other condemnations were recorded. An industrial strike was averted here, after slaughtermen had expressed concern to their own health from the disease following a heavy condemnation rate in the first carcases slaughtered.
Prior to these two consignments, AES had consigned up to 1000 porkers from his property in 1972-3 for slaughter but had had no adverse reports with regard to Tuberculosis.
The owner has approximately 2,800 acres of land, of which 2,100 are at Canowindra and 700 acres at Woodstock, some 25 road miles away. He is a cattle-dealer, pig-raiser and wheat-grower, and had reared pigs on his Canowindra property for the past 35 years. There is no movement of cattle from Woodstock to Canowindra or vice versa, and normally the pig enterprise is contained in a 900 acre unit of the Canowindra property, where range-rearing and feeding is practised.
With such high condemnation lates for T.B. occurring, a detailed investigation of cattle and pig movements was undertaken shortly after quarantine was imposed. Comparative Avian and Mammalian tuberculin testing was done twice on the 85 brook sows and 3 boars on the property, but no reactions were obtained.
Specimens from the 1973 Blayney and Cowra abattoir consignments were forwarded to Glenfield V.R.S. for bacteriological work and especially for the identification of the species of Mycobacterium involved. This was necessary from the epidemiological point of view because, apart from the (now extinct) flock of 30 range-kept highly inbred domestic poultry on the farm (which could roam at will amongst the pigs), the proximity of the Belabula and Lachlan Rivers to the farm meant that a tree-lined haven was close at hand for thousands of wild birds. These had descended in their thousands in Spring 1973 to take advantage of a profuse food supply from many acres of immature unharvested cereal crops on this farm and many of his neighbours; harvesting had been hindered by wet paddock conditions and many cereal crops were wasted because of this. Apart from this birdlife, 2 house-cows (T.B. tested negative three times) 9 working dogs (fed on dry biscuits and left unchained at night) and a stock horse of undetermined age, were resident on the farm. Also, 180 mixed sex yearling cattle had been recently brought to the farm from Orange and Merriwa districts. They were, however, grazed over parts of the property without any possible contact with the 900 acres over which the pigs ranged and no tuberculin testing of them was undertaken. Their subsequent slaughter was not attended with any T.B. condemnation.
V.R.S. reports eventually (February/March/April 1974) indicated that M. bovis was the species involved in the pig condemnations. The system of pig-raising on this farm is described as follows:—
Boars, sows and suckers range freely and graze the green feed, cereal grain and stubble available over several medium-sized paddocks within 400 metres of the homestead. The poultry flock had wandered at will in these paddocks and roosted each night in peppercorn trees and groves in these paddocks. Natural service of course prevailed amongst these adult pigs, and whenever a sow was expected to farrow a moveable half water tank was shifted near her, to act as her lactational headquarters.
When the piglets were ready for weaning (6-7 weeks) they were herded together into grower groups of 200 or so, and moved into paddocks away from their parents. There they were fed daily on 'sterilised' meat meal, grower pellets and otherwise allowed to graze on their open paddocks, gathering whatever green-feed, cereal grain and crop stubble they might need. Watering was provided in ordinary farm dams, of which one was available for each grower group. When sufficiently well grown for marketing they were inspected and the better grown animals were drafted off and moved to slaughter.
There was no regular rotation of grower groups around the several large paddocks available to them, but they were shifted to wherever the 'best feed' was available at the time, although there was always a vacant paddock kept between any two groups of growers. It was from one of these grower groups that the condemnations had arisen and at the time of initial visit some 340 porkers were still in this group, a younger group of 100 or so was also present on the farm at the time.
In the spring of 1973, a problem of Bloat and Grass Tetany had occurred amongst Cowra-Canowindra district cattle herds, because of the bumper growth of pastures in that Spring following the dry summer and autumn preceding. It was eventually discovered that several farmers on adjacent farms had donated the bodies of bloated cattle to this farm and that these had been 'plonked' in a 30 acre lane. The older grower group had been allowed to scavenge and devour these bodies, and eventually the bodies' remains had been collected and burned.
4 steers had come from JH's property, a property of 3,000 acres (1, 200 hectares) where about 1500 cattle of various origins were kept and which is about 3 miles away. 2 heifers had come from BF's property, where 100 cattle from local saleyards were run and which is about 4 miles away. 2 heifers had come from JC's property, where 100 cattle of various local origins were kept about 2 miles away, 2 cows had come from WF's stud property of 280 head, immediately opposite EAS on the other side of the road. Finally, several bodies had come from AF's property of 130 cattle of mixed origins, about 2 miles away.
Tuberculin testing of these cattle herds was undertaken and 5 N.V.L.s came from BF's property 1 N.V.L. from AF's property and 5 ex 130 tested (2 O.L.s, 3 N.V.L.) from JH's property; all the others gave negative testing results.
Since then, tuberculin testing on JH's property has been undertaken. In May, 1974 168 reactors ex 1,539 were detected; in August, 1974 a further 68 reactors were detected; in December 1974 a further 20 were found and in February, 1975 a further 8. of the 264 reactors slaughtered, 45 have been found to be spreaders, 165 have had O.L.'s classification and 52 have been N.V.L.'s. There have been cows, bulls, calves and yearlings and bullocks involved in this, but most infections have been encountered in the cows of this herd, (200-odd cows, 5 bulls, 19 steers and bullocks, and 28 vealers).
The origin of cattle on this (J.H.'s) property had not been recorded in the first 5 years of its owner ship. From 1969 a series of resident managers had purchased cattle and tended the cattle population for the 5 years until Christmas 1973 in the owner's frequent absence, but since Christmas, 1973 he has been in semi-permanent residence on the farm, commuting between Sydney and Canowindra. The farm had an extensive lot-feeding enterprise in 1971-3 and for some as yet undetermined reason there had been no traceback to the property even though batches of yearlings - fat bullocks have apparently been slaughtered off the property at 3 - 4 monthly intervals for some time previously.
