Making the most of your vaccines
Tuesday February 12 2008
Using vaccines to control serious disease in your sheep flock is a good idea in terms of maximising production.
Vaccines can be sensitive and in order to get the desired effect, correct and timely administration is essential. During February and March, hundreds of thousands of Euro will be spent purchasing vaccines for the mid season lambing ewes. However, many farmers will be administering vaccines without fully understanding how they work.
The primary purpose of your vaccine is to act as an insurance policy to prevent loss/poor performance when a disease strikes. The vaccine is generally a form of disease given to the animal in a state in which it will not cause serious disease but will stimulate an immune response. This immune response will produce antibodies against the disease which are stored in the body. These antibodies are the defence mechanism that the sheep will have if it is challenged by the actual disease. Producing antibodies is a slow process and in general full immunity will only be achieved a number of weeks after the complete vaccination course is given.
Dead Vs Live vaccinations
There are different vaccines for different diseases. It is important to know what type of vaccine you are giving. Live vaccines are generally a once-off treatment (orf vaccine or toxoplasmosis vaccine are examples). Because these vaccines are alive, it is important that they are stored properly and used promptly. These vaccines actually give the animals a mild form of the disease so accidental self injection is a serious matter and medical help should be sought if this happens. Remember that the use of live vaccines for orf etc. may introduce the disease onto the farm, so it should only be used if there is a high risk.
Dead vaccines are products that contain dead or deactivated forms of the disease which do not cause disease but still stimulate an immune response such as the Clostridial vaccines.
Building up immunity
Vaccines are not a magic injection that cause the animals to become immune to disease. There is a long and complicated process that must happen within the animal over a period of time which will result in immunity.
Points to remember
- Vaccines will only provide immunity if administered correctly.
- Live vaccines have a short shelf live. If used after the expiry date do not expect to achieve immunity to the disease in question.
- Reduce animal stress to ensure that the immune system is working to full potential.
- Vaccinate all animals in the flock with the prescribed course.
- Giving one shot (where a two shot primary course is required) is a waste of time and money.
- No vaccine results in 100pc immunity in 100pc of the sheep.
- Avoid contamination of the vaccine during the procedure.
- Observe the time frame for booster vaccinations (usually 4-6 weeks apart initially and then annually). If booster shots are not received within the stated timeframe, the animals return to the unvaccinated status and the whole process needs to start again.
- Immunity derived from maternal antibodies are only passive (four to eight weeks) and a full vaccination programme will have to be initiated for sheep kept in the flock. Treating offspring from vaccinated dams too soon after birth will result in maternal antibodies impeding the vaccination process.
- Ensure that ewes are fed adequately in late pregnancy so that they have a good supply of colostrum for the lambs and that lambs receive colostrum in the first 12 hours of life (target: 10pc of bodyweight).
- Where maternal immunity is being sought, give the ewes their annual booster four to six weeks before lambing.
- Michael Gottstein
