DAIRY COW DISEASES

Hokitika Guardian, 28 January 1929, Page 2

DAIRY COW DISEASES

RESEARCH WORK IN NEW ZEALAND. WHAT AGRICULTURAL DEPARTMENT DOING FOR FARMER. AUCKLAND, January 25. A paper was read to-day before the Agrcutural section of the Science Congress by Mr C. S. M. Hopkirk, Officer in Charge of the Veterinary Research Laboratory at Wallaceville, which proved of very great interest to farmers. The paper gives the result of laboratory and field work in dairy cow diseases, and is in reality a progress report of the team of veterinarians, Messrs Dayus, of Waikato, Webster, of Taranaki, and Hopkirk and Gill, of Wallaceville, who ai’e investigating cattle trouble. Naturally much of the work is negative in character, but is none the less valuable on that account. Three diseases were dealt with, mastitis, abortion, and sterility, in that sequence. Sretptococcic mastitis was at the outset stresser as a. contagious disease with no differentiation as far as the farmer was concerned into a non-con-tagious and contagious iform. A description of the causative organism showed that the New Zealand differed from the American form by its action on blood’'probably quite a minor point, and stress was also laid on the difficulty of classifying organisms of the group to which the mammitis germ belonged. Investigational work is proceeding on three lines. 1. Diagnosis ’of the disease. 2. Paths 6f infection. 3. Treatment and prevention. Diagnosis was necessary in order to free herds from the disease. Various methods had been given a trial, including indicator test papers, and blood tests, but the method par excellence was that of microscopical examination of a sample. By examination of a sample of milk from the quarter, the observer could say whether the condition was acute, subacute, or chronic. It bad been Ifound that only a very few quarters were ever free from all germs normally and that the usual inhabitant was a harmless one, hut one which if inflammation occurred, was liable to increase in number. Many workers ■were prone to think this saprophytic organism one of the chief factors in mammitis, but the present workeis thought 'otherwise. One point was of special interest and that was ouce a

cow had been infected with mammitis she usually remained infected in a chronic state with a. return to the acute or subacute condition at intervals. Therefore a large percentage of cows were infected in New Zealand sheds. Paths of Infection. Setting up the disease experimentally was found possible in only one way of many attempted and that, by inoculation of the causative genn into the teat sinus. The best material to use was infected milk from chronic or acute cases and not cultures of the organism. If few organisms were injected the disease appears in 5 days, in many, 12 hours were sufficient. A theory was put forward to show the way in which the udder became infected, and this, in short, was the necessity for two factors, the injury Of the quarter and the presence oif the streptococcus. The peculiarities of the organism in media of acid or alkaline reaction was considered to have a distinct hearing on the problem as the injury whatever it might he was the cause of an acidity which raised the pathegenit ity of the streptococcus. Milking machines were considered to be a helpful means of spreading the disease if wrongly used not only because of the injury caused to a quarter but because of the possibility of the cups actually sowing the germ into the quarter from chronic cases in the herd. The possibility of the sour milk streptococcus setting up mammitis was discussed and also the reaction of the udder tissue to introduce fluids, or to filtrate from cases of mastitis alone. Filtrates were stated to contain poisonous bodies but these were insufficient to injure anything but udder tissue. Treatment with a number of named materials, had proved useless. The description of prevention, however, was of interest because of the experiments tried out on herds with vaccines made from the streptococcus prevalent in those particular herds. Segregation of affected animals was considered to be the best way to set about prevention at present. By miscroscopical test, over five herds, comprising 155 vaccinated and 54 control cows gave the following results of percentage of maimnitis:— Vaccinated. Control. *lst examination 15.5 15.0 f2nd examination ... 21.(5 18.8 f3rd examination ~. 14.4 13.3 t4th examination ... 18.7 17.5 * Before vaccination. j f After vaccination. < Therefore there bad been in 5 herds no suggestion of betterment ol the

condition through vaccination nor bad controls shown any inclination to a higher incidence of disease than vaccinated following vaccination. A further instance was given together with a graph showing how a pro-, prietary vaccine used repeatedly was unable to stop the of mammitis in the herd quoted, the figures being:— Exam. Percent mammitis. ( Ist 31.2 at time' of vaccination. 2nd 30.0 after vaccination. 3rd 30.0 one month later. 4 tli 31.1 one month later. sth 41.7 seven months later. Contagious Abortion. A statementwas made that abortion in New Zealand was definitely due to bacillus abortuc and that in a large daiiying district where investigations bad been intensive 4.1 per cent of cows aborted, mid 11 per cent of heifers. There was found to be no general linking up ol mammitis and abortion even though the abortion organism would cause mammitis. The reason for the predilection of the abortion bacillus for the uterus and udder was because of the acid reaction of these two tissues compared with the rest of the body. Methods of spread wore discussed by other means than contaminated pastures—by means of milkers’ bands and by means of tbo bull. An interesting experiment was said to be in progioss 1 at Walllaceville where tbo bull appeared to be carrying infection, following ' infection by inoculation. Diagnostic methods were being per- ' footed and four tests were discussed, three of them blood tests and the fourth a skin test which was proving to be fairly delicate and probably better than tbo blood tests. Vaccination in New Zealand bad apparently from figures quoted proved a complete failure, though a second trial ovor a large number of boilers was in progress. Temporary Sterility. This disease w:is considered and the possibilities ol iUs being physiological or bacterial were difxowssed. Active work was stated to bo in progress in collection ol data and trial of definite methods of treatment (;») from the dietetic point, of view where a deficiency may exist, d>) Irom the physiological point ol view considering the relationship of milk producsterility, and (c) from the germ iirvasion of the uterus view point. Analysis of pastures was being undertaken on selected farms to see whether t!(i at would throw light on the trouble. • The condition at present was cointinitiated buL the essayist felt confident

that more would be accomplished shortly with sterility than with mammitis and abortion.