IMPORTANTANCE of selecting and administering the correct type of vaccine in the right way to maximise production in the sheep enterprise is vital.
With seeding finishing up locally and lamb marking fast approaching, prevention is better than the cure. 
Many vaccines provide proteins (antigens) that initiate a protective immune response within an animal. 
In most cases the immune response involves antibodies that can then block either the disease agent (bacteria or virus) or its product (toxin) so disease does not occur.
The first time an animal is exposed to an antigen, the response is slow and may not be strong. This is why in natural infection, animals still develop disease, and why many recover from disease over time.
The disease triggers an immune response that includes the production of antibodies, which then reduce or nullify the disease.
However, if the disease is severe, death or production losses will already have happened as the immune response is occurring. 
If an animal does survive, invariably the next time they are faced with the same challenge, their immune system is primed and the antibody response is much quicker and stronger – resulting in the disease having little or no effect.  This is why most animals are considered ‘immune’ to a disease after they have had it. 
Vaccination aims to generate this immune response and make animals immune without (in general) giving them the disease or experiencing the effects of the disease.
Of most relevance to lamb marking and ‘Clostridial Disease protection, almost all vaccination programs require two initial doses for it to be effective. 
If the second dose is not given to an animal shortly after the first (ideally, within four to six weeks) the protection given is short-lived and your money, time and effort has been wasted.
After these two initial doses the majority of vaccines require an annual booster (unless pulpy kidney is an issue). 
It is a good idea to time this annual booster in your ewe flock four to six weeks before lambing to obtain optimal levels of maternal antibodies transfer via colostrum to help protect newborn lambs. The table highlights the importance of boosters for sustained disease protection.
To maximise the efficacy of your vaccination program locally, there are three main timings to concentrate on depending on your operation. These are:
At lamb marking, it will be prudent to vaccinate all lambs with 6-in-1 and where ovine Johne’s disease is present, Gudair® as well. Scabby mouth vaccination (scratch) should also be considered. Erysipelas vaccination may be warranted via GlanEry 7 in 1.
At weaning (generally six weeks later), any lambs not being immediately sold should receive their booster 6-in-1 vaccination (and booster erysipelas vaccine if needed).
For ewes (assuming they have been vaccinated as lambs), a prelambing 6-in-1 booster vaccination and a GlanEry 7 in 1 vaccine should be considered. Remember, the pre-lambing vaccination should be administered ideally 4-6 weeks prior to give time for antibody production and incorporation in the colostrum. Obtaining optimal levels of maternal antibodies in colostrum helps to protect lambs prior to first vaccines. This can be administered with a pre-lambing drench.
Vaccination plays a big part in giving lambs the best start they can get. Wheelhouse AGnVET can also help in all areas of on-farm animal husbandry needs, helping agricultural communities of Bridgewater and the Loddon Shire and adjoining districts for many decades.
- Andrew Bissett, manager of Wheelhouse AGnVET Bridgewater with information and data from Zoetis and the MLA