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This article was published in 1980
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Brucellosis Eradication in the Gloucester Pastures Protection Board District
R.E. Moore, B.V.Sc., Veterinary Inspector, Gloucester
Gloucester Pastures Protection Board at 31.12.78 had 3,870 large stock owners running 295,500 large stock. Seven hundred and fifty of those stock owners were dairymen supplying six (6) dairy factories.
Strain 19 has a long history of use in the District being subsidised by dairy factories as far back as the early 1950's. At a survey carried out in 1967 it was established that 75% of dairymen were regularly vaccinating with Strain 19. It's use in beef herds was then in a minority but growing.
In 1970 its use became compulsory and free and in the calendar year of 1970, 36,000 heifers were vaccinated and remained at this figure until vaccination ceased in 1979.
A survey of dairy farms made at quarterly intervals in 1967 showed that on Milk Ring Tests carried out on bulk can supply, approximately 25% of suppliers showed negative. At the time of commencement of compulsory test and slaughter in August 1977 75% of dairies were giving negative results.
Abattoir sampling in 1975-76 revealed a 3.9% reactor rate for females bearing a Gloucester tail tag. Comparison of this figure with field surveys lead to an estimate made by a biometrician that the prevalence for the District in breeding cattle was 0.56%.
At the time of commencement of blood testing in August 1977 records available included property records of abattoir and property bleeding from 1973, Milk Ring Tests for dairy herds from 1972 and vaccination records since 1970.
The first round of testing began in August 1977 and finished in June 1979 with 168,079 animals tested on 3,147 properties, locating 1,102 positive reactors in 543 herds. This gave figures of 0.65% positive animals and 17.25% positive herds. In the main all calved females with CF reactors of 4 or more were slaughtered. Isolated doubtfuls in a herd with no history were re-tested. Individual herd histories suggest that it is likely that in less than 1% of herds was Brucellosis considered to be active.
Generally testing was carried out on a face with all herds dispersed, tested prior to dispersal, and provision made for purchased animals to be tested.
Bleeding teams of three (3) men per team operated from Wingham and Gloucester with a peak of three (3) teams from each centre from February to June 1978 and currently, with one team from Gloucester and four (4) men at Wingham.
Very few herds have been a problem in eradication, with one herd requiring thirteen (13) eradication tests before moving to check testing as a result of continuing infection from a dry paddock. Two large herds have yet to reach restricted status because of management problems in mustering and testing, compounded by drought conditions.
Second round testing has discovered a few strong positive reactions in herds where first round testing and history was negative.
Only in five (5) herds has there been a carry through of infection to a second round after being confirmed free on the first round. Two of these were detected first on Milk Ring Testing.
At present less that fifty (50) herds are in quarantine and all but a few of these are restricted.
A number of factors can be listed as being responsible for rapid progress, such as:
1. Excellent owner co-operation brought about by widespread good extension and the fear of loss of overseas markets.
2. Widespread use of Strain 19 for many years.
3. The depressed meat industry enabled staff to be selected from experienced cattlemen who were capable, efficient and established good relations with stock owners.
4. Not least of these factors was the apparent low incidence of persisting infections which perhaps may be an effect of climate, compared to other countries with a cold, wet climate with intensive housing and grazing.
With the benefit of herd history and experience of second round testing, many of the initial reactors detected were in my opinion from Strain 19 but this loss was only a small price to pay for the benefit it gave in reducing the prevalence of the disease.
Almost all reactors now coming forward are from young vaccinated animals and with the help of I.H.L.T. titres, herd histories and repeat testing, either lose their reactions with time or are classified as not infected.
The biggest problem has been one of management, mustering of rough country and frequency of testing of cattle in low condition. Also the problem of actually testing cattle during an extended or all the year calving season, when cows calving or with young calves, will not travel. In large herds all reacting animals are drafted off different mobs and held as one unit, and even if classified as negative, owners are keen to slaughter either at once or as soon as condition allows.