CONTAGIOUS MAMMITIS.

Hauraki Plains Gazette, Volume XXXVI, Issue 489, 21 October 1925, Page 3

CONTAGIOUS MAMMITIS.

GOVERNMENT TEST OF VACCINE. RESULT OF EXPERIMENTS. (From the New Zealand Journal of . Agriculture.) Contagious Mammitis affecting cows was again prevalent during the season of 1924-25,, more especially in some parts: of the North Island. During the .official year ended March 31 last 1613 milk samplers (more than double those: of the preceding year) . were received at the Wallaceville . Veterinary Laboratory for examination. Of these, 40.2 per cent, were found to be from cases of cpntagiouis mammitis, 16.4 per cent, not definitely of the contagious form, and the remainder,” 43.4 per cent., unaffected. ... Two vaccines prepared in New Zealand and said to possess prophylactic r value came into-’--prominence during . the year, and it'was? arranged that they be given exhaustive tests by the- ■ department at the veterinary labora- ' tory and in the field; Naturally, such experiments take some considerable time to bring to finality, and complete results are not yet available. In the meantime farmers will he well advised to exercise, great caution in ac- < cepting: intereisted statements and '-'spending money on the vaccination of their cows. There is' great risk in resting under a false sense of security, and thereby neglecting ordinary preventive measures. • Owing to the great interest taken in this matter,’ and the demand' for .... information, the -'department has decided to publish results of the tests so far as they have gone. The following interim report by Mr C. S. M. Hopkirk, B.V.Sc., acting officer in charge of the veterinary laboratory, _ brings' .this information up to the beginning of. last month (September) : HAMILTON COMPANY’S VACCINE. In January, 1925, the Hamilton Vaccine Company- supplied ,*he Wallaceville Laboratory with' their vaccine for trial under experimental conditions in that the disease is given artificially into known quarters of the udder, with'defihite quantities of milk . from infected cows, or with definite 7 quantities-of a culture Of the specific organism of contagious mammitis. That the dosage was. hot top large is show by the fact that control cows .—i.e., cows not vacciated —were able . to throw off the disease just as quickly: and effectively as the majority of the vaccinated cows. During the trials hand milking by careful milkers has been resorted to, and the animals have been well fed Ik. and sheltered, as well, as rugged. Following are- details oL the work up to date of writing:— \ Experiment A:—Three cows were chosen from' the laboratory herd,- each by microscopical examination of its milk, to be free from mammitis. Twri of these were vaccinated, and the third one left unvaccinated as a «• ' control. A month after administration . of the final dose, when it :is claimed by the company that, vaccinated cows 1 are at the height of their resistant power (immunity), the two finst cows were inoculated with mammitis-in-fec.ted material —one with culture,, the other with milk from an acute case of the disease. The control cow .Was at the, same time inoculated in the same way in two quarters, one with culture, the- other with the same milk supply. All three < cows contracted ■ the disease. Result. —These cows< were , watched for some months until they dried ’off, and will be watched again after calving. The quarters infected with cuL , ture cleared, up after a short" time, no advantage as regards time. The quartern in the vaccinated and control cows infected with- mammitis milk remained infected for some months, but, before drying, off, the control cow cleared up, leaving the vaccinated cow still affected with the disease. Experiment B.—Six' heifers were obtained from Moufnahaki in March, 1925, and .were chosen only after microscopical examination of milk' from their quarters showed? freedom .from contagious mammitis organisms. Their history also showed them to be .... free from the disease. These cows were vaccinated and kept from three to four weekts. Four were mechanically infected, while two were left to ' pick up the disease naturally, if possible, by;milking along with affected cows. A control cow; not vaccinated, was also, chosen from the laboratory herd, she also having been proved free from mammitis ab the commencement of the experiment Result.- Neither of the two vaccinated cows which were not infected artificially contracted the disease. The control cow cleaned up quickly, » as did three of. the vaccinated cows. The fourth vaccinated cow continued, until she dried off; to give organisms of contagious mammitis and inflammatory cells in her milk, although the milk iteelf was of normal colour. One of the three vac'cinsrted cow’s, although apparently sound, r flared up again, just when drying off, into an acute attack. The complete result of this experiment will .be known, when all these cows have . calved, which will not be till the end of the year. Experiment C. —Four more cows ■ were obtained locally in July of .this year, and three of these were vaccinated, the fourth acting as a control. These cows were proved to be free, from mammitis in'the quarters used, although one cow had been ■ horned while in transit All these cows contracted mammitis, both from culture inoculation and from injcc- . tibn-of.milk from an acute case of 'contagious mammitis, but it -is too early to 'give further results from test, except to state that the control cow was by no means the worst affected one of the batch. Experiment*D.—A fresh batch of eight cows, due to calve, shortly, has ■been set aside at Ruakura State Farm 'for experimental work with the Hamilton Company’s material. It will be some time before results can be obtained from this experiment. AUCKLAND VACCINE. , For testing this vaccine four cows were procured locally in May last. Three were vaccinated as required by

the proprietors .of the vaccine, and a fourth was left as control. < The cows were then left ten days in order to produce the optimum immunity, when they were. artificially infected. All took the disease in each quarter.inoculated. ‘Some quarters were given -cultures, others milk from acute, cases of the disease. The incubation period for those inoculated with culture appeared to be four to- six days. Result. —At time of writing these cows are still in milk, and the latest examination shows that two of the vaccinated cows have cleared up for the time being in all quarters. One vaccinated cow and the control cow are still affected in one quarter. CONCLUSION. Although the experiments are incomplete, in that it is advisable to wait a full season and until calving has taken place for final results, sufficient time has elapsed, so far as these trials are concerned, to show that vaccination with the two phophylactics reported upon has not given the expected immunity, and that cows vaccinated have no greater resistant powters to infection than those not vaccinated.