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Sunday 4 December 2016

Do not let the cost hinder clostridial vaccinations

Andrew Kinsella

Published 01/02/2011 | 05:00

The regional veterinary laboratories (RVL) provide a really useful service to livestock producers. Farmers, through their local veterinary surgeons, can submit carcasses and associated specimens, such as blood, faeces, placentas etc, for disease diagnosis.

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Each month the RVLs produce a report on the most interesting cases that they have encountered. These monthly reports are readily accessible on the Department of Agriculture website, www.agriculture.ie.

What caught my eye on scanning through last year's monthly reports was the number of times that clostridial diseases were diagnosed as a cause of lamb deaths. The clostridial group of bacteria cause eight different diseases in ewes and lambs, including Lamb Dysentry, Pulpy Kidney, braxy, Blackleg and Tetanus.

Once precipitated, the disease occurs so rapidly that the animal is usually found dead before any treatment can be considered. However, on the positive side, there are well-established and excellent multivalent vaccines (ie, 7-in-1 or 8-in-1 products) available to prevent all these diseases. I do not know why, perhaps questionable economics, but many flock owners have discontinued routine clostridial vaccination that was considered an essential part of good flock management 30 and 40 years ago.

Breeding ewes, replacement ewe lambs and rams require comprehensive cover against all the important clostridial diseases and so should be treated with a 7-in-1 or 8-in-1 vaccine.

Unvaccinated flocks or ewes of unknown status require a primary course consisting of two injections four to six weeks apart. Subsequently the flock will require an annual booster that is given about four weeks pre-lambing. Flocks with an extended lambing period (six weeks or more) should be split into early and late lambers and vaccinated at the appropriate times.

Immunity

The annual booster protects the ewe herself and elevates antibody levels in the ewe's colostrum. Lambs acquire their immunity through these antibodies in the colostrum. No clostridial antibodies are passed to the developing fetus by way of the maternal blood supply. In order for the lambs to acquire sufficient immunity, the ewes must be vaccinated and ewe-feeding pre-lambing must be adequate for quality colostrum production.

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Colostrum affords clostridial protection to the lambs until they are about 12 weeks of age. In order to maintain maximum immunity thereafter, the lambs themselves will need to be vaccinated with two doses given four to six weeks apart.

Full immunity does not develop until about two weeks after the second injection. In other words, if there is a history of deaths in 14-week-old lambs due to clostridial diseases, the first dose should be given at around eight weeks.

As finishing lambs require protection mainly against Pulpy Kidney, Tetanus, Blackleg and Braxy, vaccinating with a 4-in-1 is an option at this stage and may be more cost effective.

Replacement ewe lambs on the other hand will require a 7-in-1 or 8-in-1 but two doses at this stage will act as the primary course and they will require the annual booster in subsequent years.

Disadvantages

Some farmers have a routine of vaccinating the lambs when they reach three or four weeks of age instead of vaccinating the ewes pre-lambing.

This practice has a number of disadvantages, which include:

  • The lambs have no clostridial cover, in particular to lamb dysentry and tetanus, for the first weeks of life -- it is only after the second injection (ie about six or seven weeks) that full protection is achieved;
  • There is the possibility of colostral antibodies/vaccine interference if the lambs are vaccinated too early. Follow the manufacturer's instructions;
  • Very often the ewes receive no cover and are at risk;
  • It is likely to be more expensive. Administering the primary dose plus the pre- lambing annual booster to the ewe requires 6ml of vaccine compared to 8ml when the vaccine is administered to a pair of twin lambs.

One last point. Shop around when buying vaccines. I know of incidences where farmers have saved 30pc on the price of the very same vaccine product by making a few phone calls.

Andrew Kinsella is a sheep farmer in Rathdrum, Co Wicklow. He is a former sheep specialist with Teagasc

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