For many years, cattle showing external manifestations of actinomycosis, actinobacillosis, cancer and tuberculosis, have been known as "suspects".
The Cattle Compensation Act (1951-62), (New South Wales) makes provision for the payment of compensation under certain specified conditions, to the owners of cattle suffering from specified diseases, including those referred to above.
In order that post-mortem results will be available, and where practicable, there shall be no unnecessary wastage of meat or compensation payments, arrangements are made for the slaughter of "suspects" at abattoirs, under the supervision of trained Meat Inspectors. Reports on the post-mortem examinations of these suspects are made available to the officers who consign the cattle for slaughter.
Reactors to the tuberculin test are similarly consigned to abattoirs so that post-mortem reports are also available in these cases.
The areas included in this survey are as follows:
Area No. 1: (Eden Pastures Protection District)
This area extends from the Moruya River in the north at about latitude 37.75°S, to the Victorian border in the south at about latitude 37.5°S and from the main mountain range in the west to the coastline. Its altitude varies from a maximum of about 4000 ft. to sea-level. It is intersected by several ranges extending in an easterly direction almost to the coastline. Most of the higher country is unoccupied forest, the foothills of which are devoted largely to beef cattle raising. The lower country in the river valleys is devoted chiefly to dairying though some vealer raising from beef breeds or half-breeds is practised.
Returns to the P.P. Board list about 90,000 cattle in the area with dairy cattle, almost all of which are Jerseys, predominating. The most popular beef breed is the Hereford with only very small numbers of Angus and Shorthorn breeds.
Area No. 2: (Cooma and Bombala Pastures Protection Districts)
This area falls within the same latitudes as Area No. 1. It consists of the southern portion of the Southern Tablelands with altitudes varying between 2500 ft. and 7300 ft. above sea level, though stock are not depastured above 5000 ft.
The area is stocked with sheep and beef cattle. There is a total of about 90,000 cattle with Herefords predominating, the balance being chiefly Angus or Shorthorns. There is practically no commercial dairying.
Summary of "suspects" from Area No. 1
|Breed||Cancer Eyes||Sarcomas||Other Cancers||Actinomycosis||Actinobacillosis||Tuberculosis||Totals|
Summary of "suspects" from Area No. 2
|Breed||Cancer Eyes||Actinomycosis||Actinobacillosis||Other Cancers||Totals|
|H'fords & Cr'breds||132||168||36||59||20||22||2||1||190||250|
Dissecting out the figures for the two periods for both areas the disease incidence on a percentage basis may be summarised as below:
|Area No. 1||Area No. 2||Area No. 1||Area No. 2|
|Cancer of eyes||21.4||64.8||24.7||62.2|
Table IV below shows the contribution by the principal breeds to the total suspects in each area, figures being expressed on a percentage basis:
|Area No. 1||Area No. 2||Area No. 1||Area No. 2|
In an attempt to ascertain the contribution that breed makes to the disease incidence in suspects, figures were extracted from the two areas to compare, on a percentage basis, the contribution of the different diseases in Herefords and Jerseys. Insufficient numbers of other breeds were available for these to be significant. See Table V.
|Area 1||Area 2||Area 1||Area 2||Area 1||Area 2||Area 1||Area 2|
|Cancer of eye||48.7||69.5||47.7||67.2||4.5||-||-||-|
Taking the two areas together an estimate is given of the total population of each of the main breeds and the annual incidence of the diseases earlier considered.
|Breed||Number||Annual Disease incidence per 10,000 of total population.|
|Cancer of Eye||Sarcoma||Other Cancers||Total Cancers||Actinomycosis||Actinobacillosis||Tuberculosis|
For several reasons this paper does not truly reflect the incidence of the listed diseases in the overall cattle populations.
(a) Some suspects, because of advanced disease, poverty or distance from an abattoir are destroyed on the properties. As the postmortems in these cases are somewhat cursory and many are per formed by partly trained staff, these figures have been excluded.
(b) The cattle populations and their breed components are estimates only and are based on the returns made by owners of their rate able stock as at December 31 of each year.
(c) Tuberculosis has occurred chiefly in Jerseys. The very limited testing during the period in question was confined almost entirely to dairy herds in Area 1.
The widely differing disease incidence in Areas 1 and 2 (Table III) appears to be influenced chiefly by breed composition as shown in Table IV and Table V.
Assuming a Hereford population of 15,000 in Area 1 and 68,000 in Area 2, the annual incidence per 10,000 of the diseases listed would in Herefords, be:
|Area 1||Area 2|
These figures reveal a higher incidence of Actinomycosis in Herefords in Area 1 than in Area 2, though the positions are apparently reversed in the case of Actinobacillosis and possibly in cancer of the eye. No evidence is available to suggest why this is so, but there is a suggestion that cancer of the eye of Herefords is higher at the higher altitudes.
In the absence of accurate figures as to breed components in each area, it has been found impracticable to compare the incidence per 10,000 head of disease in the two areas though an attempt has been made to assess this over the entire population in the two areas combined.
The estimates made in Table VI show the abnormally high incidence of eye cancer in Hereford cattle and a fairly consistent incidence of Actinomycosis in all breeds. The figures available for the other diseases are very small but do not reveal any significant breed differences.