LIVESTOCK

New Zealand Journal of Agriculture, Volume 101, Issue 1, 15 July 1960, Page 63

LIVESTOCK

FROM 1910 to the present day there has been steady development I in the livestock industry following the outstanding discoveries of research workers which opened the road to production goals undreamed of by the pioneering generations of farmers. Under the spur of still more modern techniques developed at major research stations and applied by advisory workers in the field, the annual yield of animal products from New Zealand farms is still increasing so that now the problem has become one of marketing with, however, the comforting thought that improvements in animal husbandry and disease control can now lead to reduction in costs, which is all important in competitive selling on the world's markets.

PROMINENT among the changes which occurred during the period under discussion, were: Stabilisation of breeds of cattle and sheep, with specialised breeds taking the place of dual-purpose animals. Recognition of the importance of trace elements and the development of practical methods of overcoming deficiencies of these substances. Control of disease in livestock by vaccines and by improved remedies,

culminating in the 1940 s with the appearance of the first of the antibiotics, the use of penicillin to control mastitis in dairy cattle. Parallel with these developments improved methods of feeding livestock became established with the abandoning of the old “feast and famine” method of farming in the more progressive districts. Though there are still some areas in which dairy cattle are turned out to fend for themselves during winter, most farmers now pay

special attention to fodder conservation and to all-the-year-round management of pasture. They realise that only by so doing will their stock grow, produce, and reproduce satisfactorily. Very Few Outbreaks of Serious Disease Between 1910 and 1960 there have been very few outbreaks of diseases which are recognised overseas as major problems of animal husbandry. Anthrax has occurred on a very few occasions. Swine fever has been known twice, indicating the very real need for the Department’s rigid control of garbage fed to pigs. ; Foot and mouth disease and rinderpest have never been introduced into this country. Throughout the years the Department has relied on importation restricted to approved countries rather than on quarantine to preserve New Zealand’s immunity. Though this policy has sometimes appeared irksome, it has been amply justified by results and the livestock industry of this country has developed to a most satisfactory state without being exposed to the dangers accepted as part of farming in many countries.

Conquest of Bush Sickness

IN such a period of major development it will be possible to select only a few of the most outstanding achievements to indicate progress, which is still continuing. Typical of such success was the conquest of bush sickness, a name which is rarely heard today, though in the 1920 s it signified a mystifying deficiency; it took out of production vast areas of easily worked country on which stock simply would not thrive for any length of time. In November 1911, B. C. Aston (Agricultural Chemist, Dominion Chemical Laboratory) wrote a comprehensive article on bush sickness with a special footnote: “The term bush sickness is quite a misnomer. The condition may develop on land that has been cleared of bush or forest for over 20 years.” Aston stated definitely that “evidence adduced by veterinary officers of the Department over the period of 14 years that they have been cognisant of the matter goes to show that the condition in stock known locally as ‘bush disease’ or ‘bush sickness’ which occurs in the Rotorua, Matamata, and Tau-

ranga Counties (longitude 176° E., latitude 38° S.) is not a disease in the proper sense of the term, but a physiological condition resulting either from: (a) a food supply wanting or deficient in some essential nutrient, which therefore results practically in starvation; or (b) a food supply con-

taining naturally or adventitiously (1) some toxic compound, or (2) some normal constituent present in abnormal quantity, resulting in chronic poisoning.” At this stage it had been shown that animals removed from the affected

areas began to recover as soon as they were placed on sound country. They showed no known bacterial infection and no transmitted disease. Aston therefore asked: “1. Is there any poisoning, present in the animal, in the food, or in the soil? “2. Whether such poisons (if present) are there in amounts which would be injurious under the conditions prevailing on the ‘sick’ country? “3. Is there a want of balance in the food constituents, organic or inorganic, which would result in the condition complained of?” Gilruth (the first Chief Veterinarian of the Department) had earlier described the condition as one of “progressive anaemia” so that the stage was set for the chemist to determine the cause. In his article Aston reviewed known deficiencies and also discusses the type of soil known to be bush sick: “They are invariably soils consisting largely of pumice and other ejectamenta comparatively recently blown out of the bowels of the earth and scattered by the wind over a large area . . .” Need for Patience Later Aston made a remark which is equally applicable today: In investigating an obscure disease one must not expect immediate results or be impatient if some definite answer is not at once forthcoming from experiments. He went on: “In a case such as this, where the onset of the ailment is so long delayed, taking perhaps months, it is only reasonable to suppose that the abnormality in conditions which is the cause is not very greatly removed from absolute normality, and it is this fact which inspires most hope that a practicable remedy may be found— by altering the animal’s diet in some way, the cause of wasting may be counteracted.” How right Aston was. Not until 30 years later was the cause of bush sickness revealed as a result of work done in Australia on a similar condition by Filmer* and Underwood. The research of Filmer and many other scientists into cobalt deficiency in New Zealand vindicates the faith that Aston, pioneer in deficiency diseases, held in 1910. During, the years of trial and error hundreds of experiments were carried out to answer the questions voiced by Aston: Why should ruminants be affected and non-ruminants always remain perfectly healthy? Would it be fairer to attribute the sickness to unsatisfactory farming than to any defect of the soil or food?

Experimental work had been forecast in the November 1910 “Journal”, when it was mentioned that five experimental paddocks had been selected and fenced in various parts of the bush sick area. It was intended to treat these paddocks with various dressings and to observe the results.

In August 1912 C. J. Reakes* discussed the progress of investigations into bush sickness as he had decided to call the trouble. A veterinarian,

J. Kerrigan, had been stationed at Rotorua and a great deal of experimental work was done both in the field and in the laboratory. Reakes started the classical “mistake” at this time, when he referred to the fact that ... a deficiency of available iron is probably responsible for the trouble, and though it would be premature yet to affirm certainty on this point, it certainly looks most promising. In any case the field of investigation has now been narrowed down considerably and I consider the outlook particularly hopeful. It was noteworthy that no mention was made in this report of the type of topdressing applied, though it was stated that three young steers had been kept healthy for 15 months when “controls” run on similar but untreated paddocks had long since died. In April 1913 Reakes again reported on the experiment and mentioned that the three steers were still doing well after two years on plots treated with 7 cwt of superphosphate per acre. Two other steers had remained healthy for two years on paddocks treated with Malden Island guano at 10 cwt per acre. A ewe kept on the area for 16 months was also healthy. Early Optimism At this stage Reakes was most hopeful and set out the results of the experiment in detail in the June 1913 issue. Lime apparently had no beneficial effect, but superphosphate and iron sulphate showed some promise at Mamaku. Reakes summed up: A study of these experiments . . . indicates that the best results were obtained, in the case of cattle, with soil dressings of (1) superphosphate, (2) sulphate of iron, (3) blood and bone (with luxuriant herbage ploughed in), (4) guano (with luxuriant herbage ploughed in); in the case of sheep, with (1) sulphate of iron, (2) basic slag, (3) superphosphate. At that stage it was not appreciated apparently that young sheep are most affected by bush sickness (cobalt deficiency). In the same article, however, are words which should have given the key: The good results obtained with sheep from sulphate of iron used as a topdressing were rather seriously discounted by a later experiment conducted at Te Pu, where ewes placed sometime before lambing in paddocks topdressed with this, died a few months later, together with their lambs. . . The sheep used in this trial were from land adjacent to bush sick country, which was probably what we now know as marginal cobalt deficient country. By 1914 the experimental farm at Mamaku had become well established.

160 acres being in use. Drenching daily with syrup of iron phosphate gave spectacular results (see illustration on page 65). It was not recommended, however, that this treatment be used; even then emphasis was placed on methods of topdressing to supply the mysterious substance lacking in the soil. It was now firmly decided that heavy dressings of superphosphate would prevent the condition and that iron deficiency was a basic cause. In 1915 there is the first mention of a preventive lick which was used in experiments at Mamaku. The ingredients given for the lick were “perchloride of iron, common salt, sulphate of calcium, and hydrate of calcium”. Research was now concentrated on the best method of supplying readily available iron and the right type of topdressing to use. In 1916 the Department would not recommend dairying on bush sick country, though at Mamaku such farming had been carried on successfully, and during the next few years it became evident that topdressing with superphosphate alone was not sufficient to prevent bush sickness. Experimental work with iron compounds went on steadily and in April 1919 Reakes and Aston discussed the use of a combined iron and ammonium citrate known as ferriammonium citrate, which was quicker in its results than the syrup of iron phosphate. Aston was by this time calling the disease “iron starvation”, and in a long article in the April 1929 “Journal” there is the first mention of dosing with ground carbonate of iron. Topdressing Helps Superphosphate and basic slag topdressings had certainly proved the usefulness of phosphatic fertiliser, but the iron-lack theory was now so firmly established that there is no mention in any of the numerous articles of any other possible deficiency. The quantities of the ferriammonium citrate used were growing fast, as it was considered that 1 lb of citrate would keep a cattle beast healthy for a year. In the early 1930 s ragwort became a menace on the pumice country and combined with bush sickness against the settlers. It is interesting to note Aston’s comment in July 1930 on ragwort-eradication experiments by C. R. Taylor (now Instructor in Agriculture, Rotorua) with various chemical compounds, including, sodium chlorate and mixtures: . . . these provide evidence that ragwort, which is considered locally a great danger and cumulative with bush sickness in preventing the settlement of pumice lands, need no longer be feared.

Aston's Prescience This article of Aston’s is of particular significance because in it he disposes of the various theories proposed during the year by what he called “various experts”. These theories varied from calcium deficiency in the soil to poisonous elements in the soil or pastures. Aston clearly linked the deficiency present in bush sick country with that seen in sand dune soil type in New Zealand and Tasmania, in the gravel country in Nelson, the volcanic ash in Kenya, and. the Cheviot hills in Scotland. He believed firmly that the deficiency was a simple one and that it was associated with open-textured soils. In this he was correct. All energies of the research worker were now devoted to obtaining the most effective and cheapest form of iron. At this stage limonite ore was being obtained from Whangarei. It was the softest crude ore available and easily powdered. The mineral was provided as licks, as it has no objectionable taste, which had made the citrate hard to administer. There was now no attempt to use a manurial mixture containing iron, as the licks were proving satisfactory. Cobalt Cure In 1935, however, following the publication of Filmer and Underwood’s work in Australia, interest was focused on cobalt. These authors had claimed that iron free extract of limonite cured enzootic marasmus in Western Australia; this disease was the same as bush sickness. Work done here by Grimmett and Shorland, however, was less conclusive, but the first experiments were small. Attempts were made to have selected farmers use cobalt drenches, but Hopkirk in the June 1937 “Journal” complained: Farmers in all areas where bush sickness was known to exist in cattle or sheep had become accustomed to feeding out limonite-salt licks, and on this account were rather loath to undertake the additional work which a drenching experiment would entail. Experiments were started at Mamaku and Arohena, and results showed that cobalt did prevent bush sickness if given regularly once or twice a week. Hopkirk concludes: . . although drenching with cobalt has been tried experimentally, it is not a practical method of control of bush sickness, as the labour involved is irksome and impossible when numbers of sheep have to be kept in health. The training of sheep and cattle to take limonite licks of high cobalt content is, as yet, the only practical means of controlling the mortality.

The “as yet” was highly significant, because Cawthron Institute soon proved that cobalt was readily taken up by pastures. C. R. Taylor in an article in the September 1938 issue gave this conclusion: The administration of cobalt to stock through the pastures by topdressing with cobaltised superphosphate is an effective and economic means of combating bush sickness in those areas where topdressing is applied annually as a routine practice. A most satisfactory result was thus achieved after almost 30 years of continuous investigation. Much remained to be done, however, to determine the most suitable amounts of cobalt to use and the best time to apply the dressings, but the main battle was over. Bush sickness was no longer a serious disease where topdressing could be applied. However, as at that time topdressing was not always practicable and as cobalt was scarce during the war, further work was done on drenching trials, and in October 1941 Filmer commented: Drenching at monthly intervals with very large doses of cobalt will keep ewes and lambs alive on bush sick country and will even cure bush sickness. Aerial Application Licks were also effective, but the best method of supplying cobalt was through the pastures. In the November 1947 “Journal” Andrews and Prichard* showed that applying cobalt from the air was a practical proposition. In this work a solution of cobalt sulphate was used, but this meant that large quantities of water had to be carried, which could be difficult in hill country. By 1950, however, aerial topdressing was an accomplished fact and the problem of applying cobaltised superphosphate to hilly country had been solved; 1 cwt of cobaltised superphosphate mixture containing 6 lb of cobalt sulphate to the ton was shown to be a sufficient annual dressing. There remained the puzzling fact that only ruminants were affected by cobalt deficiency, but this was solved during 1948. Andrews in a comprehensive article in the March 1956 “Journal” stated: . . . British and American workers isolated a new growth factor which they called vitamin 812,B 12 , and found it contained cobalt. All higher animals need the vitamin, cattle and sheep apparently requiring more than do the other animals. In cattle and sheep vitamin 812B 12 is elaborated in the rumen or paunch by microbes. For this purpose they use the cobalt naturally contained in feed. If

cobalt intake is lower than normal, production of vitamin 812B 12 is restricted and unthriftiness results. .. . . n • Marginal ueticiency The problem of acute cobalt deficiency had now become merely historically important; only areas in which the soil is marginally deficient remain a problem to this day. It affects chiefly the rearing of young sheep. Calves

are not nearly so susceptible. As Andrews put it: There are> however> areas where the cobalt content of soils is only mildly to moderately deficient. Still other soils have been tentatively described as marginal or suspected cobalt deficient. Within the areas represented by these two groups mature cattle and for the most part calves and mature sheep remain in

apparent good health, but young growing sheep can become affected to a greater or less degree. . . Unthriftiness usually appears between the third and sixth months. . . . A map in the article referred to indicates by shading the cobalt status of New Zealand soils. This, of course, gives the broad picture only and is intended as a guide. The article stresses that if cobalt deficiency is suspected the most conclusive method of diagnosing it is to assess the response of animals to supplements of cobalt administered by mouth. ' Trace element deficiencies are often very complex. In recent years cobalt, copper, molybdenum, and now selenium have been involved. Sometimes two or more deficiencies can occur, but the story of bush sickness illustrates very definitely the persistent and patient work necessary to produce a satisfactory solution.

Copper Deficiency

THOUGH it had been known for many years that dairying on peat country had its difficulties and that periodic spelling of stock off the farm was necessary to maintain them in good condition, nothing which indicated that a deficiency of copper could be present in New Zealand soils was published in the "Journal" until 1944.

THE few paragraphs in which copper was mentioned referred to its use in controlling internal parasites and there were dire warnings of the dangers of copper poisoning, particularly in sheep, which cannot tolerate a high copper intake. In the last 16 years, however, the position of copper as an essential element has become known and, though there have been some arguments over the relative roles of copper and molybdenum, it can safely be said that copper is essential in animal nutrition. The clue that copper might be deficient in certain areas, particularly in peat soils, was first seen when the role of copper in worm drenching was considered. The December 1944 “Journal” contained an article by Dr I. J. Cunningham, Wallacevile Animal Research Station (now Assistant Director-General of Agriculture) in which he discussed copper in the following terms: The practice of drenching with bluestone and nicotine sulphate arose from the known deficiency of these materials in dealing with internal parasites, infestation with which was argued from the scouring symptoms. When, however, the

present series of investigations into peat land scouring were undertaken it was realised that the curative properties of bluestone were capable of another interpretation. In short, the effectiveness of bluestone treatment suggested the possibility that an actual dietary deficiency of copper might exist, and that this deficiency might be the cause of the disease. There was further proof that copper deficiency existed, said the article, “when the Government veterinarian at Hamilton, Mr H. Doeye, diagnosed enzootic ataxia (irregular gait) in lambs bred on peat soils similar to those on which scouring occurs. This disease of lambs had previously been described in Australia and England and was known to result from an insufficient intake of copper”. The symptoms of peat scours —continuous watery yellow-green scours, particularly when there is any flush of feed, poor milk production, etc. — are well known to farmers on this class of country, but less well known are the troubles associated with beef cattle, such as loss of coat colour and shy breeding. In adult sheep little is

seen, but lambs may become paralysed soon after birth. It was surprising that the possibility of copper deficiency had not been considered earlier than the 19405, but research workers have made up for the late start. Cunningham in his first article in 1944 said copper could be supplied by: 0 Drenching with bluestone solution. o Addition of bluestone to the drinking water. 0 Licks. 0 Topdressing paddocks with bluestone. In the September 1946 “Journal” there is a further article on topdressing with bluestone. In this early work it was mixed with J per cent by weight of slaked lime or other inert substance to promote free running when used as an aerial topdressing. An obvious inference in this article was that larger aircraft than the Whitney Straight used would enable larger quantities of copperised fertiliser to be used. These copperised topdressings are available today and are the accepted method of applying copper to peat lands. In an article in the October 1948 issue Cunningham said “practically all reclaimed peat land in New Zealand is deficient in copper. . . .” And later adds: “There is a total of some 400,000

acres of copper-deficient peat throughout New Zealand.” Much of this known copper-deficient country has been mapped and farmers in these known areas regularly supply supplementary copper to pastures. By 1954, however, complications had arisen and in the April “Journal” of that year Cunningham says: Copper deficiency in New Zealand was first recognised about 1940, causing unthriftiness, low production, and disease in cattle and sheep pastured on reclaimed swamplands. Soon it was learnt that copper deficiency was not always the full story for in some areas molybdenum also came into the picture. An excess of this element, especially when associated with a low supply of copper, was responsible for some of the disease symptoms. On peat lands therefore two disease states were recognised: the first, a straightforward deficiency of copper and, the second, a copper deficiency accompanied by poisoning due to excess molybdenum in the grass. Peat was not the only soil type to be affected: “Further work has shown that copper deficiency with or without molybdenum poisoning is not confined to peat soils. Sandy soils, marine and alluvial silts, and other soils . . . are also affected. At present about li million acres of farmed land are known to be involved and about an equal area not yet developed is regarded as likely to prove deficient.” The problem had grown. Much work had to be done on molybdenum, finding the type of soils in which a dangerous excess of this mineral occurred and determining how

to prevent the toxic action of molybdenum. Cunningham’s 1954 article commented on the interaction of molybdenum and copper: It is known that copper and molybdenum act against each other inside the animal. An excess of molybdenum in the ration tends to drive out stored copper and to interfere with the use that can be made of the copper present. On the other hand extra copper in the diet will, within limits, neutralise the effect of excess molybdenum. The position is even more complex, for Australian workers have recently shown that sulphate, in its turn, affects molybdenum storage in the body and if sufficient sulphate is present, molybdenum is got rid of quickly. In Somerset, England, there is a similar disease to our peat scours called “teart” due to excess molybdenum, but our copper deficiency is not quite allied. A high molybdenum excess causes scouring, as in teart, but in New Zealand a low copper intake, plus some excess molybdenum, produces a similar condition. Cunningham goes on: For copper deficiency with or without excess molybdenum a method of treatment or prevention is to increase the copper supply. Prevention should be the objective, as it is the only method that gives results against enzootic ataxia. The scouring symptoms of peat soils can be removed by a short course of dusting with copper solutions, but unless a regular supply of copper is given throughout the year, thrift and production will not be improved. By 1957 it was possible to inject copper as a copper cerate to control

the disease. Cunningham in the September issue of the “Journal” in that year lists the dangerous soils and their approximate areas (where known) and states: There are clearly large areas in New Zealand which produce pastures high in molybdenum. [lnvestigations had by this time proceeded very far from those up to 1944.] . . . the similarity of chemical composition of pastures from [all] the soils listed . . . suggests the strong possibility that disease controllable by supplying copper could occur on any farm situated on any one of the soils. It is, indeed, likely that such diseases already occur but have been overlooked because they might not recur every year and because the unthriftiness, the greying [of the animal’s coat], or the scouring have not been recognised as signs of a ' - disease. The situation now is changed. It is known that when these signs occur in cattle, it is probable that they are caused by too much molybdenum and too little copper in the fodder, and that probability is very high indeed if the cattle are kept on any of the soils named. It is advisable therefore for farmers on these soils to keep this possibility in mind when inspecting their stock. Copper cerates are effective and economical for treatment of single animals or whole herds. This is not the whole story, as there are a few areas in which copper in large quantities has apparently not prevented a disease which has the appearance of copper deficiency. Work is still going on, but for most of the known areas the recommendations in the 1957 article have proved satisfactory.

Control of Disease by Vaccination

VACCINATION effectively controls some diseases of both animals and man, but no example emphasises the limitation of vaccination as a means of disease eradication better than does blackleg, an acute and generally fatal disease of calves and sheep. Blackleg is one of the group of gas gangrene diseases characterised by the production of gas in the tissues and death from the toxic products liberated by invading bacteria. Clostridium chauvoei, the cause of blackleg, is a spore-forming bacillus and the spores survive in the ground for years to perpetuate the disease.

"DLACKLEG spores arrived in New * * Zealand with unsterilised bone fertiliser from India about the end of last century. The disease was first noticed in Taranaki and is first referred to in the “Journal” in February 1916, in which attention is drawn to an amendment to the Blackleg Regu-

lations. Formerly these had applied only to Taranaki, but the disease had spread to Auckland Province, and parts of the following counties were also declared infested areas: Franklin, Raglan, Piako, Thames, Ohinemuri, Waipa, and Waikato Counties.

Later in 1916 C. J. Reakes, then Director of the Livestock Division, fully described the disease (which had become . well established) and its control. At this time and for many years blackleg was thought to be limited in New Zealand to calves. “The disease,” said Reakes, “fortunately is present only in limited areas of New Zealand, but the mere fact of its limited distribution renders it necessary to take all possible precautions to prevent its further spread and at the same time to keep it under control in the already affected localities. This can be done effectively at but slight cost and with but little inconvenience to farmers, provided they cooperate with and assist the departmental officers in carrying out the necessary measures.” Discussing the introduction of blackleg into the country Reakes said:

In Taranaki, so long ago as 1889, isolated cases were found in a small area where this fertiliser [imported bone manure] had been used, and for several years no cases outside this area were noted.' Then the disease began to spread rapidly, and it became necessary to take proper measures to get it under control. These measures have proved remarkably satisfactory. and effective. Danger from Imported Manures The vaccination programme certainly prevented wholesale deaths, but the damage was done and the disease was too deeply rooted to be eradicated easily. Unsterilised bone manure had been a prohibited import since 1905 and sterilisation had been subject to rigid inspection. Finally in 1932 importations of animal manures from India were prohibited; it would have saved endless trouble and expense had these manures never been admitted, for with them also came anthrax, though fortunately this occurs to a very limited extent. Blackleg control at the time of Reakes’s article in 1916 was complicated. Areas in Taranaki and Auckland Province were designated “Infected Areas, A or B”. There were restrictions on the movement and sale of young cattle in these areas and permits were required. Cattle could be compulsorily vaccinated, and in A areas no young cattle could be moved or sold unless vaccinated. It is strange to read of these precautions and to realise that at the same time thousands of wounded servicemen were dying from gas gangrene (which was one of the worst “killers” of the First World War) when inoculation would have prevented losses for which medical science, lacking the blessing of penicillin, had no answer. Reakes says of calves with blackleg: “Medicinal treatment, from a curative point of view, is of little or no value, and the one effective • measure is prevention”. Use of Vaccine By 1918 Wallaceville Laboratory, as the Animal Research Station was then known, had increased the output of blackleg vaccine to 226,000 doses, almost double the number issued in the previous year, to cope with the extension of blackleg control to Auckland Province. In 1919 the infected areas were increased in size so that much of Auckland Province and all of Taranaki were involved. Inoculation against blackleg began to decrease in the 19205, some 103,000 doses being used in 1921 and 86,000 the following year. In 1924 the annual report of the Livestock Division stated: The need for vaccination of calves is still apparent, but it is satisfactory to report that the disease does not

show any increase, nor has it extended to other districts. The continuance of the restriction on the movement of calves out of the .. quarantine areas is necessary in order to safeguard clean districts. In 1926 it was suggested by the Department that regulations could be relaxed: The number of actual deaths reported as due to blackleg is very small compared with the volume of work entailed in general vaccination. No case of • blackleg has occurred in Hawera district for over three years. Malignant oedema, a disease caused by bacteria which are close relatives

of the blackleg organism, and which caused confusion for many years between the two diseases, is first mentioned in the 1929-30 annual report of the Wallaceville Veterinary Laboratory. At this stage the modern type of blackleg vaccine was developed and proved effective. Sheep Also Affected By 1941 the number of calves vaccinated had dropped to 10,000 in Taranaki and 22,000 in Auckland Province. However, outbreaks still occurred among calves, there being 200 in Auckland Province in the year with 395 deaths. The November 1941 issue carried an article by M. B. Buddle, then Veterinary Research Officer (now Superintendent) at Wallaceville, which was to alter completely the previous conception of blackleg in New Zealand.

Up to this time it had been, considered that the blackleg organism did not affect sheep and that deaths in sheep from “blood poisoning” following shearing injuries, dog bites, etc., were due to malignant oedema and not to the true blackleg organism. Buddle mentioned, however, that: “Observations over the last few years have indicated that true blackleg [in sheep] is apparently widespread throughout New Zealand, and it has been observed in districts where the disease has not been reported in cattle”. In describing the disease Buddle refers to possible confusion with malignant oedema and the necessity for correct bacterial diagnosis of the cause of the mortality. Vaccination with blackleg vaccine would have no effect ' against malignant oedema, but he says: ... When heavy annual losses from the disease occur on a property following castration and docking in lambs or following shearing, expertments have shown that these animals could be protected by vaccination carried out a fortnight before these operations. Vaccination has been shown to be very effective in preventing losses from a spontaneous form of the disease occurring in hoggets and is thus analagous to the disease in young cattle. In the April 1944 “Journal” the veterinary notes gave further emphasis to blackleg in sheep by describing the characteristics of the disease and stressing the need for diagnosis by trained personnel. Since blackleg is similar in effect to anthrax, a disease fortunately rare in New Zealand and quite unknown in sheep here, and to tetanus as well as to “blood poisoning”, it was necessary to be sure of the diagnosis before inoculation took place. In 1944 the “Journal” announced that vaccination when warranted was done free by the Department. Because of the volume of vaccination this policy was soon to become inoperable. Buddle’s. next article on the disease (the “Journal” April 1948) continued to press for urgent diagnosis of suspected outbreaks in sheep and to reiterate an essential factor in control of the disease: It is particularly important in the control of blackleg that the carcasses of animals which die from the disease should be deeply buried or burnt. As the organisms are present in great numbers in the carcass and in discharges, failure to dispose of the carcass properly perpetuates the disease on the property and intensifies its incidence. 1 ' Wise words, which had been repeated from the earliest days, but

the disease had become so widespread by 1948 that only regular vaccination on infected properties offered any control of losses. Vaccination Methods A full description of vaccination methods was given by C. V. Dayus, Livestock Superintendent, Dunedin, in the May 1949 issue and a very complete discussion of blackleg in sheep by I. M. Cairney, Veterinarian, Dunedin, in the May 1950 issue. The latter drew attention to the “great practical importance” of the slight difference between different types of bacteria ■causing gas gangrene and commented: “There is an effective vaccination to protect sheep against blackleg, but there is no such vaccine for combating blood poisoning”. The story of the occurrence of blackleg in New Zealand and prevention of it is excellently rounded off by

a comprehensive article from M. C. Armstrong, Veterinarian, Timaru, in the December 1953 issue. By this time intra-muscular injection of penicillin had enabled treatment of actual cases to be effective and on affected farms prophylactic treatment with penicillin of unvaccinated ewes was advised if the animals had had to be assisted with lambing. Vaccination of calves was now being done on a voluntary basis, as the Blackleg Regulations had been revoked in 1952, because blackleg was found to occur outside the known infected areas. One case had even been diagnosed in the South Island, near Christchurch, and Northland farmers at this time were becoming agitated. Vaccine could now be purchased for vaccinating sheep, but the order revoking the Regulations in 1952 still

noted that: “A procedure is being set up under which vaccination will be done by veterinary surgeons employed by farmers’ veterinary clubs as well as by Inspectors under the Stock Act 1908”. Restricting the vaccination of calves to those qualified to diagnose the disease gives some protection from the disastrous possibility that an outbreak of anthrax in cattle, though fortunately very rare in New Zealand, could be confused with blackleg. Vaccines are now prepared commercially and mixed vaccines that protect sheep against blackleg and other forms of blood poisoning at one inoculation are freely available. Control, but not eradication, of blackleg is now a fact, but for over 60 years the disease has been a constant menace on a large number of farms.

MASTITIS —A Menace No Longer

MODERN therapeutics have had an amazing impact on mastitis of dairy cattle. Formerly a disease of the greatest importance to dairy farmers, mastitis has now dwindled to the status of a "nuisance". Such has been the effect of use of penicillin and later-developed broad-spectrum antibiotics on infected udders; and though the disease is still with us and occasionally becomes troublesome and refractory to antibiotics, it is no longer the cause of early culling of valuable cows. Antibiotic treatment has certainly prolonged the average useful life of dairy cattle in this country.

THE changed outlook on mastitis (often in earlier times referred to as mammitis) is well illustrated in the “Journal” over the past 50 years. Between 1910 and 1945 there were 22 references and articles; since 1945 only three issues have carried articles specifically dealing with mastitis, all describing its treatment by antibiotics. Young farmers have no conception of the difficulties which faced past generations of dairymen who struggled with mastitis control schemes; they know nothing of the hopelessness of attempting treatment with hot fomentation and massage during a severe outbreak. In December 1910 (vol. 1 of the “Journal”) H. A. Reid, Officer in Charge, Wallaceville Veterinary Laboratory, wrote: It is difficult, with any degree of accuracy, to appraise the monetary loss incurred by the presence of contagious mastitis, but those who

have had the misfortune to encounter its ravages are in a position to appreciate what the loss must amount to in the aggregate. Contagious mastitis may unquestionably be held to be one. of the most insidious and persistent pathological conditions met with in cattle of this country. . .

Reid describes experiments with vaccines, but concludes: “The treatment though probably beneficial seems likely to mislead and renders efforts to control the disease less effective.”

Much time and money were to be spent later on vaccines and onl> the antibiotics eventually ended their production. Four years later, C. J. Reakes, then Director, Livestock Division, (later Director-General) , . warned . farmers that no reliable cure had been developed: • The only persons who have committed themselves to the definite assertion that they can satisfactorily treat contagious mammitis are the vendors of patented preparations for its. treatment, and these, it is presumed, make their business pay, the farmer finding the money therefor. But I cannot blame the farmer altogether for this. He is in a difficulty, and he tries to get out of it. However, the position is clear, and the reliable treatment for contagious mammitis has still to be discovered. Forty years later an almost .“reliable” treatment had been perfected. Reakes laid down some . preventive measures and recommended hygiene: “When a milking machine is used the cups should be well rinsed in clean, fresh water after being removed from each cow ...” Treatment at that time was mainly one of washing with disinfectant, massage with belladonna ointment, and drenching with Epsom-salt. Hot fomentations also were recommended for acute cases. Such methods required many hours of work, and this at a time when most dairy farmers were still clearing stumps between milkings. It had been suggested by Reid that farmers should notify cases of contagious mastitis, and we find Reakes in the August 1915 “Journal” advocating the following as desirable measures: (1) To schedule the disease in the Stock Act, thus rendering it necessary for an owner to notify it should he know or suspect a case in his herd; (2) To make it obligatory that any cow proved to be affected with the disease be branded with an official brand before she can be allowed to go off the owner’s place. One can imagine what would have happened, in the light of later incidence of the disease, had these recommendations been adopted. Further in the same article Reakes expressed himself forcibly about the claims made for patent medicines: The only drench I know of which can be relied upon to put an end to contagious mammitis. . . would be one containing enough poison to put an end to. the cow also.

In the February 1922 “Journal” Reid gave details of various experimental methods of treating mastitis: Drenching with formalin and udder injection with colloidal metals, with chloramines, and • with various dyes tested during the First World War'on wounds. General treatment was also prescribed: Needless to state, in addition to the udder injections the patient must receive local and general treatment. This comprises in addition to the general well being, relief of painful internal. symptoms by hot fomentations to the udder, followed by massage with sedative liniment, application of wetpacks and suspensory bandage in certain cases, and saline laxatives internally. Such treatment of half a dozen cases would be a full day’s work. The general conclusions were that the results of the experiments were disappointing. The standard Departmental adviceat this time was to dry off and fatten affected cows to prevent their becoming centres of infection. By 1925 there had been systematic trials of preventive vaccines prepared by proprietary companies. C. S. M. Hopkirk, Acting Officer in Charge, Veterinary Laboratory, Wallaceville, in an interim report in the September “Journal” stated: ... sufficient time has elapsed ... to show that vaccination with the two prophylactics reported upon has not given the expected immunity, and that cows vaccinated have

no greater resistant - powers-; to infection than those not vaccinated. At this time over 2,000 milk samples annually were being received at Wallaceville to determine the presence of mastitis. These were sent mainly by individual farmers. A brief statement in . the October 1931 issue announced that the Livestock Division of the Department of Agriculture had initiated, a systematic method of dealing with contagious mammitis in dairy herds and a number of farmers had agreed to carry out the method. This was the beginning of the great attempt to limit the spread of mastitis within herds and to classify cows by regular microscopical examination of milk samples, and so grading them that clean animals were milked first, slightly affected cows next, and definitely affected last. ■ ■ “The grouping system of milking dairy cows commenced last year . . . has given promising results,” said the 1932-33 annual report (quoted in the December 1933 “Journal”). Fifty herds were involved and farmers were advised to begin this method of mastitis control. By 1936 a subsidiary laboratory had been opened at Hamilton for milksample examination, but research went on. In March 1938, shortly after the “Journal” had been enlarged in size and scope, it. presented a well illustrated article which indicated the measures being adopted to alleviate mastitis in infected cows. About this time the brom-thymol-blue test was

introduced to enable farmers to separate infected cows from clean animals, but it failed to live up to expectations. Drenching, frequent stripping, and massage were recommended. The depressing picture of mastitis was shown by a section of the Department’s annual report, published in the November 1938 “Journal”: Mastitis continues to be a cause of much loss of production among dairy herds not only in infected animals, but also from a culling or replacement point of view. . . The prevention and control of the disease through herd and shed management must continue to be given first consideration. In the March issue of the following year, the Acting Director of the Animal Research Division wrote: “The mastitis-control scheme which has been operating [in the Waikato] during the past eight years has been critically reviewed . . . and it is considered that this scheme will need considerable revision before it can be applied generally.” In the March issue of 1945 Hopkirk, in the last article of the pre-penicillin days, cautiously stated: “Present day knowledge is too incomplete to lay down definite rules for prevention. However, considerable benefit will accrue by observing rules of cleanliness and common sense.” One of the rules he advocated is sensible, but difficult to carry out: “Heifers should enter bails first for milking, then clean cows, and finally known affected animals. It is preferable to keep special bails for heifers.” Such a routine is difficult to maintain conscientiously, because a supposedly clean cow may develop mastitis overnight and so upset the programme, and cows are creatures of habit. Improved drugs, however, had become available and sulphanilamide drenches and also injections of acriflavine into the quarter were mentioned. Farmers of that day will remember sulphanilamide-in-oil and how difficult it was to handle. The availability of penicillin in the form in which it came into general use was announced by R. W. Roach, then Veterinary Research Officer, Ruakura, in the July 1948 “Journal”. The drug had been tested in various ways in the previous season and in 1948 it was possible to put it on the market in a water-soluble cream containing a dose of penicillin sufficient to deal with normal infection. The Livestock Division had conducted demonstrations to farmers all over New Zealand so that all interested were conversant with the

requirements. It seems astonishing, now that there are tins of penicillin and other antibiotic tubes in every cowshed in the country, that the initial demonstrations took place only 12 years ago. A warning about the risk of the development of penicillin-resistant —precisely what happened later, when the H-bug became a serious problem given by J. F. Filmer, Director of the Animal Research Division in the August 1949 “Journal”. He wrote: ... if too small a dose of penicillin is given, or if treatment is stopped too soon, the more susceptible germs are killed, but the few more resistant ones survive and in the absence of competition they multiply rapidly. Therefore all cases should be treated early, a full course of three tubes should be given and the whole contents of one tube should be injected at each treatment.

Penicillin treatment of cows at drying off was also discussed in this article. The use of larger doses of penicillin or of other antibiotics, such as streptomycin, was discussed in the November 1955 “Journal”. This article again warned about the deleterious effects of milk containing penicillin on cheese making: “If 300,000 units of procaine penicillin are injected into infected quarters, the milk from two or three of these quarters at the next milking will inhibit starter in a 900gallon vat.” Mastitis control has come a long way since the days when foments and massage were all that stood between production and culling. Farmers should appreciate the rapidity with which the benefits of this overseas research reached the milking, shed. What is taken for granted now was unknown only 12 years ago. ■ ■iiiiitiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiih

Tuberculosis of Farm Animals

“Tuberculosis is prevalent to a sufficient extent amongst the cattle of this Dominion to merit the serious consideration of the subject by every stockowner ...” So wrote J. A. Gilruth (1910) in the first paper to appear in the “Journal” on tuberculosis of animals, a paper which is remarkable for its clarity and comprehensive range.

GILRUTH pointed out the deadly dangers to public health and to livestock from drinking tuberculous milk, a warning which did not fall on stony ground, for in 1911 the results of a pasteurisation demonstration at Glen Oroua factory were reported by C. J. Reakes. Pasteurisation plants were installed in several factories, especially to safeguard whey and skim milk for animal feeding. The adoption of pasteurisation at such an early stage sealed off effectively a serious source of spread of the disease. ' Reakes, writing again on tuberculosis in 1913, warned that pigs contracted the disease through access to cattle droppings on pastures and that in spite of pasteurisation of whey and skim milk, farmers required to take precautions in management to limit the spread of the disease. International Commission The findings of the International Commission on Bovine Tuberculosis given in detail in the May 1911 “Journal” have been the backbone of eradication techniques throughout the world to the present day. Control is discussed under two different conditions: 1. Where a herd is free from tuberculosis and is to be kept so. 2. Where one or more animals in the herd are infected and the purpose is to eradicate the disease and establish a sound herd. General precautions given are that animals showing clinical evidence of the disease should be promptly eliminated, all milk from tuberculous cows that is used for food should be pasteurised, and when diseased animals are found the stables from which they are taken should be thoroughly cleansed and disinfected. British Legislation The introduction of a Milk Bill and Tuberculosis Order in Britain is reported in the May 1913 issue of the

“Journal”. Speaking at a large meeting of dairy farmers at Salisbury, England, called to consider the new legislation, a Mr Sadler, addressing the meeting said: Why, in the name of Goodness should not the people who send us butter and cheese from foreign countries be put under the same regulations?

In the next decade no references to eradication of tuberculosis are made, but, naturally, during the First World War little could be done. A brief official note in 1920 informed the New Zealand farmer that the Argentine had introduced a compulsory tuberculin test for cattle imported into that country.

Tuberculosis in Poultry The first reference to tuberculosis in poultry was made by Gilruth in 1910 and F. C. Brown (1921) gave the symptoms of the disease and described it as the most serious the poultryman had to contend with. In 1924, 1927, and 1929 the same author detailed measures to be taken to eradicate the disease, and no doubt his advocacy of wholesale burning of affected poultry and subsequent methods of manage-

ment could well have contributed to the relatively low present incidence of tuberculosis in poultry. Tuberculin Test In 1925 the “Journal” recorded extracts from the annual report of the Director of the Livestock Division on the incidence of tuberculosis in animals in which reference is first made to the use of the tuberculin test in New Zealand. The test was largely used free of cost to the farmer on a voluntary basis on cows supplying milk for human consumption. The report shows that of 397,432 cattle examined at the works 5.41 per cent were found to be tuberculous. In 1927, from a similar report, the expansion of tuberculin testing and the increased awareness of the farming community in reporting “clinical cases” were considered to be beneficial in the prevention of spread of the disease. About this time new techniques of tuberculin testing and improvements in the production of tuberculin were being developed overseas. C. S. M. Hopkirk (1926) recorded experimental trials of testing techniques recommended by the British Medical Research Council carried out at the Wallaceville Veterinary Laboratory. It is interesting that the caudal fold test (the standard test used today in New Zealand) proved equally as reliable as the cervical double intradermal test. Comprehensive Review After ten years, ten years of economic depression, T. A. Blake (1936) in an excellent article reviewed all aspects of tuberculosis in farm animals. He pointed out research work done in Scotland and England where of 365 tuberculous children under five years of age 50 per cent were infected with the bovine type. At the same time he acknowledged the effect of the Stock Act 1908 in controlling to some extent the disease in New Zealand. Of the farming community Blake stated: The enlightenment of the farmer and his knowledge concerning tuberculosis, combined with his very sensible readiness to report and cull suspected animals, have been a most important factor in the suppression of what might have become a far more serious problem had the owners of our herds been apathetic and negligent in this matter. In the last sentence in his article Blake sounded the tocsin for the next 20 years:

New Zealand could not put forth such gigantic effort as has been demonstrated in America, and. naturally, it would not be required; but it might be possible in the near future to carry out some plan of elimination in certain areas as a preliminary step to greater things. E. J. Simmons (1938) warned pig keepers of the dangers of pigs becoming infected with tuberculosis. Bovine tuberculosis in relation to its spread to humans was succinctly described in contributions by the Department of Health in 1939 and again in 1943. D. Marshall (1940) in discussing tuberculosis in pigs and poultry drew attention to the many sources of infection which still remained within the Dominion. The Director of the Livestock Division (1941) recorded that 14,458 cattle were tested voluntarily at the owners’ request and rightly pointed out that though the system of clinical inspection supplemented by biological testing of composite milk samples was in existence, only by the tuberculin test could eradication of the disease be accomplished. A. G. Brash (1943) described the symptoms of tuberculosis in bovines. A. C. Howse (1949) ably reviewed and brought up to date the position of tuberculosis of poultry and I. G. Watt (1951) reiterated the dangers to humans of bovine tubercule infection. Momentous Steps In 1945, however, the first momentous step was taken to control bovine tuberculosis in cattle by the passing of an amendment to the Stock Act making tuberculin testing in town milk supply herds compulsory. The voluntary cooperation of producers mentioned in Departmental reports had led to this legal action being taken. The progress of the scheme was summarised in the “Journal” in 1952 by the Minister of Agriculture. Various factors had prevented the rapid implementation of the scheme, but for the year up to the end of January 1952, 57,952 cattle in town milk supply herds had been tested with a reactor rate of 6.6 per cent. The Minister drew attention to the comparatively large numbers of slightly infected animals and to the priority given to the testing of herds supplying raw milk for human consumption. Reference was made to the further institution of heat treatment stations, so that 85 per cent of all milk sold in urban areas was pasteurised.

Factory Supply Herds The Minister pointed out the great importance attached to tuberculosis eradication in overseas countries and concluded with a reference to consideration being given to the introduction of a scheme of eradication in factory supply herds. “The step to greater things” visualised by Blake (1936) had been taken. The most comprehensive article in the “Journal” on tuberculosis of farm animals up to 1952, the year in which it appeared, was by P. J. McCann. McCann gave an up-to-date description of tuberculosis in cattle, pigs, sheep and goats, horses, dogs, cats, and poultry. The methods of infection and spread of the disease were recorded and the tuberculin test and ■ its use described. Successful methods of control and eradication in other countries were dealt with and the author concluded that: . . . eradication of the disease from cattle in New Zealand is an objective worthy of the greatest and most persistent efforts. Reviews of tuberculosis in poultry were written by Howse (1955) and M. E. White (1955), and the mechanisms whereby the disease was spread within a farm were outlined by V. E. Senior (1956). The relation of hygiene and farm management in the control of tuberculosis was discussed by A. Fisher (1959). . In 1958 the Minister of Agriculture, Mr C. F. Skinner, announced details of a voluntary scheme for tuberculin testing of factory supply herds. The Minister stated that the devising of a workable scheme had not been easy, but that the proposals would avoid undue hardship where a high incidence of disease occurred. He expressed the hope that all herds in New Zealand would eventually be virtually free of tuberculosis. A New Vista The scheme is embodied in the 1958 Amendment to the Stock Act, and opens a new vista in the control of the disease. The veterinary manpower of the Dominion is making a concerted effort to eradicate one of the most insidious diseases known to medical science. Fifty years may seem a long time. It is indeed half the time since the skills and science of Western civilisation were brought to this country. The exhortation of Gilruth (1910) has not gone unheeded; ways and means have been found to surmount the peculiar difficulties of the problem of tuberculosis in animals.

* Later, Director, Animal Research Division, New Zealand Department of Agriculture.

* Chief Veterinarian; Director-General 191836.

♦E. D. Andrews, Wallaceville Animal Research Station, and A. M. Prichard, Chief Pilot, Aerodromes Services, Public Works Department, who made the first experimental flights in aerial farming operations.