PULPY KIDNEY IN LAMBS

Dominion, Volume 29, Issue 302, 17 September 1936, Page 16

PULPY KIDNEY IN LAMBS

Effect of Ewes’ Diet on Mortality Rate SUCCESSFUL VACCINATION OF MOTHERS (By Cultivator.) The diet of ewes has a distinct influence on the incidence of puipy kidney in lambs which annually is the cause of heavy mortality. Briefly, this disease is brought about by a multiplication of certain micro-organisms in the intestine, the consequential result being the production of a very powerful bacterial poison, or toxin, in the lumen of the intestine, which is absorbed into the bloodstream. This trouble has been the subject of extensive investigation by New Zealand research workers for several years, and some valuable economic benefits' have been the outcome. It has been proved now beyond doubt that the organism responsible for causing death is widespread in nature and may be obtained from soil, grass, dust and practically anything exposed to the air. Referring to the subject in a paper prepared for the Royal Agricultural Society, Mr. Allan Leslie, F.R.C.V.S., pointed out that experiments had shown that the organism can be recovered from the digestive system of apparently normal lambs and that massive doses of the organism are not capable of setting up the disease in the healthy lamb. Results of experiments carried out at Lincoln Agricultural College pointed to the conclusion, that, if there are more factors than one that predispose the lamb to pulpy kidney, faulty feeding of the ewe during pregnancy is one of them. The effects of the poor dieting of the ewe are believed to operate in two ways. These are, first, by lowering the birth weight of the offspring and therefore reducing its nutritional condition and' reserves and interfering with its development and fitness, and secondly by influencing the quality, amount, and distribution of the yield of milk during the most susceptible pulpy kidney period. What Post-mortems Reveal, Another research worker who has been keenly interested in the subject is Mr. D. A. Gill, district superintendent, Department of Agriculture,- Wellington, who has found that when a post-mortem examination is made there is an accumulation of fluid in the heart-sack, the organs appear congested with blood, and the kidney substance may or may not be “pulpy.” Pulpiness of the kidney is not present at the time of death, but may be found very shortly afterward. Otherwise there is little to be seen at a post-mortem examination except slight changes which suggest toxemia. An affected lamb seen be-

fore death shows symptoms pointing to acute abdominal pain, and is frequently convulsed. It strains painfully and passes soft, gassy feces that are obviously abnormal. Dealing with vaccines and antitoxin in the prevention of pulpy kidney in lambs in a recent issue of the “Journal of Agriculture,” Mr. Gill stated that immediately the'nature of the disease and the identity of the microbe causing it were discovered, vaccine and antitoxin supplies were prepared and trials made. The vaccination of lambs was not a success. Antitoxin, on the other hand, is admirably suited to the prevention of this disease in New Zealand, as it occurs mainly over a period of a few weeks, and an injection of antitoxin will confer immediate and strong immunity for a short time such as that. Experiments with antitoxin, which have been made in Central Otago, have been summarised to show that among 2078 inoculated lambs only eight, or 0.38 per cent., died of pulpy kidney, whereas among 2123 control lambs in the same mobs 49, or 2.3 per cent., died. These results were obtained in 1932 and 1933 with single doses of antitoxin, the quantity injected varying from 2 c.c. to 5 c.c. Unfortunately antitoxin is costly to prepare, and except in special circumstances its use is not warranted on economic grounds, since the costs of the antitoxin per 100 lambs would exceed the value of the percentage of lambs likely to die of pulpy kidney if untreated. Antitoxin Economically Unsound. Vaccination of young lambs was proved to be impracticable and it was found that although the use of antitoxin was effective it was economically unsound. There was left, however; another line of action, that of the vaccination of the ewes during pregnancy so that the lambs would obtain antitoxin, in the first days of life, from their dam’s colostrum. This matter was the subject of trials undertaken in Central Otago in the 1935 sea son, the results of which were reviewed in a report by Mr. O. V. Dayus, district superintendent, Department of Agriculture, Dunedin. The original intention was to vaccinate approximately 1000 ewes and hold a corresponding number of controls on farms where the disease in lambs hadheen known to exist in former seasons. The vaccinated ewes were to depasture together under identical conditions. It was proposed to give the ewes two doses of vaccine, the first dose approximately six weeks before lambing and the second dose ft week or ten days before lambing. Because the vaccine was not available in time, however, the intervals had to be shortened.

Five farms were used for the trials, and in September, 1935, the first dose of vaccine was administered to 1370 ewes, the dose in all cases being 5 c.c. A total of 1352 ewes were kept as controls. For the purposes of vaccination, on each occasion the ewes were run into a race, packed fairly firmly, but not crushed in any way. The wool was parted just behind the shoulder blade and the site of injection swabbed with methylated spirits. The skin in the area was then raised and the needle of a hypodermic syringe inserted and the required dose given subcutaneously. Afterward the vaccinated ewe was marked on the head with pain?. Just under three weeks after the first vaccination, the second was carried out. the dose being 10 c.c. in all cases to 1190 ewes, the controls on this occasion numbering 1202. The cause of the decrease was

that the second vaccination was not carried out on one of the farms as the ewe-s had begun to lamb. Degree of Immunity for Lambs. The results of these trials gave rather a striking illustration of what can be done. Taking the two farms on which deaths occurred from pulpy kidney the figures serve to show that the mortality rate ie small in cases where ewes are vaccinated in comparison with the controls. On these two properties 812 ewes were vaccinated, and the pulpy kidney losses among the lambs numbered two, or 0.24 per cent. On the other hand, however, of the 840 control ewes on the same two farms, 59 died from pulpy kid ney the percentage in this case being 7.02. From these trials it appears that a considerable degree of immunity is conferred on the lamb through the colostrum of the mother. The farmers chiefly concerned are enthusiastic concerning the success of vaccination, and generally the outcome gives most encouraging support to the possibility of the successful vaccination of ewes with a vaccine prepared from colostridium welchii, type D. The laboratory examination of the colostrum and blood of lambs from vaccinated ewes would.indicate the presence of antitoxin.