DAIRY CATTLE DISEASES.

Manawatu Standard, Volume XLIX, Issue 251, 21 September 1929, Page 5

DAIRY CATTLE DISEASES.

an instructive address. (By “Ploughshare.”) At times expressions of impatienco are made at the slow progress which appears to have been made in successfully dealing with diseasoe which affect farm stock, more particularly with the more common complaints of dairy cows. The enormous annual loss which dairy farmers sustain from one cause or another naturally causes them great anxiety, and any measure of relief, either in the form of prevention or cure, would be of untold benefit. Stock diseases are, however, very elusivo when attempts are made to trace their origin and to find the remedy, especially in complaints of a contagious nature. While certain remedies appear to be giving good results in particular herds, it cannot be said that research and investigation have as yet discovered any positive cure which can be accepted for general application. Dealing with the three main scourges afflicting dairy cattle, namely, sterility, contagious mastitis and contagious abortion, there appears to be an impreseion in some quarters that these particular diseases are more or less confined to this Dominion, and that, just as New Zealand is situated in an isolated part of the globe remote from the rest of tlio world, so those who are working on tho problem are ploughing a lonely furrow without a guiding hand and out of touch, with the research being done elsewhere. This view is altogether wrong. In tho first place, these diseases, far from being confined to New Zealand, are worldwide in their incidence, and in every country in which dairying is carried on to any extent they are recognised as grave sources of economic loss; and much time and money aro being dovotod to research into their cause, treatment, and prevention wherever dairying is one of the major industries. Two years ago an Imperial Agricultural Research Conference was held in London and attended by delegates representing agricultural' interests from every part of the British Empire. Its object was to organise . and co-ordinate research into agricultural problems throughout tho Empire. One of the results of this conference was the establishment of what may bo termed an Information Bureau of Agricultural Research. A complete list of research workers in the whole Empire is published, giving names and addresses of each worker and the particular work upon which he is engaged. Each worker receives a copy. Those engaged in New Zealand can see at a glance who else is working on tho same problem as themselves and can get into direct communication with them and inter-change views and theories. At the present time Mr Gill, of the Wallacevillo Laboratory staff, i 3 on a tour of England, America and the Continent and on his return will bring first hand information on the work that is being done on these diseases in the main research centres in every country he visits, In addition, correspondence is being exchanged with workers in Australia, Africa, England and two of American universities, comparing notes and endeavouring to gain new ideas. Apart from all the organised research within the British Empire, foreign countries are attacking the same problems, and the local department keeps in tho closest touch with what is being clone, and immediately anything is published copies are obtained and translated. It will thus be seen that in New Zealand wo are at least as far advanced in tho work on these diseases as are research workers in any other part of tho world, and it is possible that we may be in some respects a trine ahead of workers elsewhere. LABORATORY FOR TARANAKI.

The foregoing is a summary taken from the introduction of an address by Mr W. M. Webster, B.Se., M.R.C., V.S., at Inglewood, who went on to say that witmn a few weeks it was oxpected to have a small field laboratory established in Now Ply* mouth with a trained assistant in charge, in order that all tho preliminary bacteriological work may be done on the spot instead of material having to spend two days" in transit to- the. main- laboratory at Wallaceville. One of the difficulties in the past in investigating these diseases closely on the farm has been the impossibility of doing all that Was desired owing to the considerable time, trouble and loss of profit to the individual fanner through holding his animals for repeated and often prolonged examinations. Arrangements have been made this season by which any farmer on whose herd repeated examinations and manipulations are carried out will be fully compensated financially for his time and assistance. STERILITY. It has become clear, says Mr Webster, that sterility is duo not to one cause, but a number of causes producing the same result. In some cases, particularly where oil or the majority of the herd is affected, it appears to be a definitely infectious dis-

ease, spread through the herd by the sire. In such instances bettor herd hygiene works a marked improvement. Attempts to treat affected cows havo been made for many years, but with no success. It appears that once a cow is affected the disease will run its course irrespective of any attempted treatment. However, a healthy sire can be kept healthy and free from infection by the simple expedient of douching him after every service. Where this method has been faithfully carried out, it has apparently given marked success. It involves some trouble, but only for a few weeks in tho season. Tho important point is that the douching must be carried out as soon as possible after every service. A certain number of cases of : sterility are a sequel to contagious abortion and aro then often permanent. I MINERAL DEFICIENCIES. In many herds where 20 to 30 per cent, of the cows only are affected the cause is at present obscure, but evidence is fast accumulating that in many cases it is due to a mineral deficiency, probably phosphorus, in the pasture. In some extreme cases it has been definitely proved that a mineral deficiency is responsible, and at the present stage the feeding of bonemeal or a lick of bonemeal and salt is strongly recommended, particularly on farms on which the land and pastures can hardly be described as first-class. A comprehensive analysis of herd testing and breeding records in the Waikato and Tara, naki 6eeins to point to some sterility being due to some limiting factor in the pasture. Largo numbers of pasture samples havo been and are being collected and analysed to settle this point. In South Africa and America it has been definitely shown that mineral deficiency is at times a cause of wide-spread sterility. The. lecturer recently received from the University of California a report of a very comprehensive survey of cattle breeding on tho large ranches in the South Western States. On some of the poorest land they got an averago calf crop of twenty-five per cent. Pasture analysis showed marked mineral deficiency and feeding bonemeal raised the calf crop to seventy-five per cent, in one season. Of course, that was an extreme case, but it is quite possible many farms in Now Zealand are on the border lino, when only the weaker concows are affected. Lime. is anothor mineral which may be responsible in 6ome cases. Experiments to prove this are at present in progress on four farms. The department has provided sufficient carbonate of lime to top-dress half the acreage of each farm at the rate of two ton 3 per acre. In return, the farmer is required to divide his herd and run one half entirely on tho limed paddock 6, and the remainder on the unlimed paddocks. Careful breeding records aro being kept. CONTAGIOUS ABORTION. Contagious abortion is one of the earliest diseases recognised amongst cattle. At the present time it occuie in every quarter of the world where cattle aro kept and has hitherto bafUed all attempts at treatment. Professor Bang himself the man who discovered the responsible germ some twenty-five or thirty years ago, and who has devoted his energies to the problem of its mastery ever since, stated recently that since the discovery of the germ very little progress lias been made. Contagious abortion is' a disease which confers somo immunity on an affected animal after she has suffered an attack and for this reason vaccination seemed to offer reasonable hopes of combating it. A tremendous amount of time and work has been spent in this direction, but the consensus of opinion all over the world at present is that vaccination is to all intents valueless in the treatment of this disease and the method is being abandoned. All cows which have aborted should be kept strictly isolated so as to prevent infection through discharges on pastures. BLOOD TESTING. By means of a simple and reliable blood test it is possible to detect any cow which is harbouring the infection in her system, whether she lias actually aborted or not. By this means it is possible to clear up any herd by disposing of the reactors to the- test. This method bus been extensively adopted jot recent years in .the United States and what are termed . “abortion-free accredited herds” are established . and provided with a Government certificate to the effect that they are tree from the disease. A farmer with such a herd can sell his stock with this guarantee which naturally enhances the value and, of course, he will not buy any stock himself except subject to passing the test. With due precaution the reacting oows need not be immediately disposed of, but can be kept on the farm provided they aro kept strict'y apart from the clean cows and never allowed to graze on the same paddocks as the latter. This method lias been put into practice with good results in several instances in New Zealand, but many farmers seem unwilling to help themselves to the extent of the extra trouble and care involved, despite the fact that the Department of Agriculture does all the blood testing free of any charge and is only too willing to advise ’ the farmer in his efforts with expert assistance at alt times. . CONTAGIOUS MASTITIS. In his references to mastitis, Mr Webster expressed the opinion that research work in connection with this particular problem was probably more advanced in New Zealand than elsewhere in the world. From tho mass of accumulated evidence it has been found that the disease is lying latent in the udders of a very large percentage of cows, and that once present the infeotion seems to persist for the remainder of the animal’s life notwithstanding that she may apparently recover. The recovery, however, is only apparent and no more and it only requires some small strain on the oow’s system to upset the balance and immediately cause the latent disease to reappear in any acute form. Dealing with the much discussed question of vaccination as a remedy, it was explained that tho germ causing the disease belongs to a class against which vaccination has never given satisfactory results. Apart from this, there is apparently no immunity or increased resistance acquired as a result of a natural attack of the disease. Consequently, the chances of vaccination proving a successful method of combating the disease are doubly poor. The department has carried out an extended scries of trials, with various types of vaccine—all on a strictly controlled basis—namely, half the herd aro treated and the remainder loft as controls. Milk samples from every cow, whether vaccinated or not, have been submitted to laboratory examination at short intervals before, during and subsequent to vaccination. In some instances the subsequent examinations have been at monthly intervals over a period of two years. The results have shown that not only has vaccination failed to produce any beneficial effect whatsoever, but it actually caused a temporary increase in the severity of the symptoms in affected cows. In the light of this evidence Mr Webster said that he had no hesitation in reaffirming that up to the present vaccination when exposed to the vigorous test of a strictly controlled trial had given no beneficial results whatsoever. MILKING MACHINES. The definite opinion was advanced that the faulty handling of milking machines was largely instrumental in developing the latent germs which are present in a largo percentage of cows and a good deal aould be done in the way of prevention if better care was exercised. Tho averago four cow plant is usually worked by two milkers and it is almost an impossibility for them to keep with the machines in stripping and bringing in fresh cows. They can keep up with the slower milkers, but the cows which give their milk more readily are almost invariably those that are the first to succumb to an acute attack to mastitis. On the other hand, when tho individuality of the cows is studied by taking off the machines as soon as tho animal is milked, little or no trouble is experienced. In badly affected herds, when this plan of close attention to the machines has been carried out it has been quietly followed by a marked improvement in the amount of mastitis, in the herd generally. Other routine precautions as regards cleanliness of hands and machines and washing of teats are also important factors which should never be neglected.