DISEASE IN STOCK

Taranaki Daily News, 11 September 1934, Page 31 (Supplement)

DISEASE IN STOCK

VETERINARIAN’S ADVICE EXPERIENCE GAINED IN TARANAKI. RESPONSIBILITY OF STOCKOWNERS In another portion of this issue the views of the Department of Agriculture in regard to animal public health are set forth. In the following articles Mr. J. Hill-Motion, M.R.C.V.S, B.V.Sc, New Plymouth, gives conclusions arrived at after considerable experience as a voterin ary surgeon practising in Taranaki. MAMMITIS PREVENTION. Consider milk stagnation as the most ’important predisposing cause of mammitis in the dairy cow, and adopt measures to avoid such a state, thus milk before calving, all heavy producing cows which put up a good “show” a day or two before calving; avoid over-stocking for market, sale or show; and dry off carefully all cows at the end of the lactation or at weaning. Hand-milking must be carefully, skillfully, and regularly carried out. Machine milking requires just as much attention, if not more, and ratiuifal and nygenic measures adopted at all times. Wash all udders before milking with permanganate of potash solution, or a chlorine disinfectant, e.g, 1 per cent, hypochlorite of soda. Dip all teats after milking m strong Condy’s solution or chlorine disinfectant. Prevent calves from sucking each other, this accounts fcr many heifers calving down with mammitis or weak quarters. Avoid in-breeding and select stock with sufficient constitution to withstand the climate in the district. Provide shelter on the farm by planting suitable shelter belts, and arrange for sufficient shelter around the holding yards. Concrete the yards, and more especially the exits and approaches to prevent accumulation of mud and cow manure. Practice at all times careful herding, slow driving and little use of the dogs. . Provide sufficient winter feed ana plenty of variety in the diet. Mouldy and badly fermented ensilage, and mouldy cooked or weathered hay are responsible for more stock troubles than anything else on the farm. Top-dress-ing mtist also be rational, in order to supply the necessary minerals for milk production and breeding. Mineral, mixtures should also' be offered occasionally, and must be given in Taranaki during, the late winter and early spring months. Common salt must be provided on all farms when feeding roots. In fact all that goes for good farming must be practiced not only to prevent the onset of mammitis but the possible onset and - spread of other diseases. Above all, careful milking is the first essential, remembering that the requirements for clean milk production are the essentials "for the control of mammitis. Wash the udder before milking, dip teats after milking, and manipulate the quarters both before and after milking to detect the early onset of trouble. Laboratory control • measures-’ may greatly assist in controlling mammitis, out cannot reliews the farmer of his responsibility. The latest reports . regarding vaccination against mammitis in Australia appears to offer useful and reliable assistance to the farmer, although further improvement is necessary in the technique and method of application of such biologies.

CONTAGIOUS ABORTION. The insidious nature of the infection and the chronic manifestion of the disease naturally permits one to assume that treatment would of necessity be difficult, and this has proved to be the case. Whereas it has been suggested that mineral deficiencies are responsible for the lowering of the natural resistance, the lack of calcium, iodine, etc. in the metabolic processes have their adherents, and accordingly treatment embodying the use of such minerals in different forms has been tried both in prevention and cure. Against this may be mentioned the increase in virulence- of different strains of B, Abortus, as perhaps an important factor in the infectivity of the organism. Whatever be the true explanation of the spread, of the disease it is difficult to ascertain with certainty, but it can be definitely stated that no line of medical treatment yet tried has given any hope of success in combating infection in the herd. The infection in the case of many individuals is frequently followed by complete recovery, when the organism is eliminated from the body, and the animal is assumed to have acquired a certain degree of so-called .immunity. Again, some cows seem to exhibit a natural immunity, and this is particularly seen in heifers, which, as calves, or even as yearlings,, have been exposed to infection and subsequently isolated before being brought in for service. This would appear to account for the lower incidence of abortion amongst first calvers in an infected herd. It has been considered by the French workers, M. Vallee and Rinjard of the National Research Laboratory, Alfort, that if an immunity is acquired it is an active immunity, or perhaps better an infection •immunity, which persists only so. long as the organism remains localised in the animal body, e.g., udder, where it has been shown no clinical manifestations can be observed, yet B. Abortus is being excreted in the milk. This is the interpretation of the immunity by the use of the B.C.G. vaccine against tuberculosis. The French workers prefer, therefore, to assume that a great many of the animals in tire herd acquire a tolerance to the infection, with the result that in subsequent pregnancies they carry their calf to the normal time, but dill act as spreaders of infection, and at the same time become chronic reactors. This interpretation of the so-called immunity would appear to offer a suitable means whereby a herd could be protected from infection when suitable immunisation methods would prove of service in preventing abortion and thus saving the calves by hastening the production of a herd immunity or tolerance.

Sera, culture filtrates, and aggressins have been tried extensively in America, but have so far failed to justify more than a continued study of such products. Bacterins or dead cultures of B. Abortus have been employed in many countries, but whether the method of preparation or the method of application have been responsible, reports although showing some success, would appear to be against the continued use of these biologies. No harm can positively result from the use of bacterins, and many authorities still have faith in the discovery of new methods of preparation of same, which will precipitate the success now long overdue./ Vaccines, or living cultures of B. Abortus attenuated or otherwise, have been experimented with in most countries, and are being extensively u&?d in prevention and control of contagious abortion. Veterinary experts in Great Britain, America, Germany, Denmark and France have shown that so far the use of these living cultures have given remarkable success in lowering the incidence of abortion in infected herds as compared with control animals, and in most of the countries mentioned this

method has been accepted as satisfactory. In New Zealand, the use of living cultures of B. Abortus or in fact, of any bovine disease is prohibited by the Stock Act of 1908 and it therefore raises the question as to whether such prohibition is wise, since most of the dairying districts of the Dominion have their full quota of B. Abortus infection, at least quite in line with such infection in other dairying countries of the world. BOVINE TUBERCULOSIS. The incidence of tuberculosis in bovines in the Dominion is relatively low compared with other dairying countries, and the explanation for this is not far to seek when one considers the fact that the dairy cow is never housed in this country and therefore the spread from cow to cow is very remote. Less than 5 per cent, is the figure usually given, but of course in some herds the incidence may be considerably higher, and farmers are therefore well advised to watch out for cases of tuberculosis amongst the dairy stcok. The cow which developes a dry cough, unthriftiness, dryness of the coat, hide-bound, and what is more important, the induration of the udder, indicated by a progressive enlargement of one or other of the hind quarters, commencing usually towards the top and growing downwards, with no previous history of a mammitis, and not heat, pain or redness. Such cases are notifiable and will be dealt with by the stock inspector of the area. The great number of house cows presents a problem which must be faced by the health officers, because the danger of human infection from such cows when tubercular is, considerable. Assuming that this selected bovine is giving tubercular milk from an infected quarter, then those consuming such milk will of necessity suffer from a mass infection, which will manifest itself most readily in the children as cases of cervical, abdominal, or articular tuberculosis. In this respect it is interesting to note that in one of the largest sick children’s hospitals in the Old Country, 90 per cent, of the cases of tuberculosis Were of bovine origin. The obvious method of eliminating the possibility of tuberculosis in the house cow is to have a clinical examination made periodically, or better still a tuberculin test performed at least at time of purchase. Again, a laboratory test of the milk sample would also assist, and more especially when an induration or hardness of the hind quarter or quarters become apparent without the history of a mammitis. From what has been said it will be apparent that the safest plan is to obtain milk for the household from a herd, where .should the tuberculous udder appear, a sufficient dilution will have been acquired before it reaches the consumer.

ERADICATION OF DISEASE. . Everyone will agree that the time is now ripe for a definite drive being made to eliminate tuberculosis from the dairy of New Zealand, and considering the value of the dairy cow at the present moment, and the small numbers of cases likely to be dealt with, it would certainly be an economic proposition for the country and of the greatest benefit so far as the sale of our dairy produce is concerned. The primary requisite to success in this tuberculosis eradication scheme must be a suitable . and reliable method of testing dairy cows for tuberculosis. Such a method is available in the shape of the tuberculin test or tests. Three such tests are in use in different parts of the world and each and every one has its limitations and its recommendations. The subcutaneous gives a thermal reaction, the intradermal and ophthalmic tests give local or clinical reactions. The latter or ophthalmic" test is usually employed in conjunction with one or other of the former. For New Zealand conditions the intradermal and apthalmic in conjunction would appear to be satisfactory, but the skill and experience necessary for their interpretation must be left to the skilled veterinarian. The administration and control of such testing would of necessity be on a large scale, unless a uniform system was devised for the whole country and the detail was left to a local organisation or even to the individual factories themselves. The benefits to be derived from tuberculosis eradication need not be elaborated on, but it will suffice to indicate that this would be the first step towards the elimination of the pasteuriser from the manufacture of our dairy produce, a procedure now being adopted by many of our competitors in the British market.