The control of porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (Mhp), was the focus of these conferences.

Dr Charlie Francisco, Director of Technical Services for ISPAH, spoke about performing slaughter evaluations of pigs immunized against PCV2 and Mhp. Slaughter evaluations are a tool to verify the overall health status of the herd. This enables one to assess the disease levels in normal pigs, unlike necropsies that only look at sick pigs.

Slaughter evaluations also permit follow-up to clinical disease outbreaks and the impact on the entire population. Necropsy exams involve very few pigs.

When health programmes or production practices are changed, slaughter evaluations give valuable information beyond production records and also identify subclinical diseases.

For the slaughter evaluations that Dr Francisco supervised, which started last year and are still being carried out, the primary objective was to compare Mhp vaccination programmes, and the secondary objective was to identify other subclinical disease.

Based on his evaluations of 17 different herds, Dr Francisco concluded that having a single dose Mhp vaccination was much better than no vaccination, but that a two-dose vaccination programme was much better. The second dose is the one that immunises the pig.

What surprised Dr Francisco most were the other subclinical diseases they found. Five of 11 herds tested had atrophic rhinitis, which was unexpected. They also found roundworms in two of the 17 herds, and mange in one of the herds.

Dr Brad Thacker, Senior Technical Services Specialist for ISPAH, gave two presentations on the effects of PCV2 and vaccinations programmes against it. He said that the objective of the ISPAH PCV2 vaccination programme – which is comprised of two doses, given at three and six weeks of age – is to prevent infection as opposed to controlling it.

The first vaccination provides some immunity but it is the booster shot that produces a huge titre response.

The focus of the programme is to prevent viraemia, which is the virus in the bloodstream, and is the mechanism for the virus to spread within the body. As more immune cells become infected, there is an increased potential for disease.

In terms of PCV2, barrows have more problems than gilts. Dr Thacker presented various studies which showed that mortality in unvaccinated pigs was much higher than in vaccinated pigs. The timing of the infection is very important, the earlier its contracted, the greater effect it will have. Later infections do not have as great an impact.

Also, PCV2 infection is enhanced by disease co-factors such as PRRS and mycoplasma.

Dr Thacker mentioned that the healthiest day of a pigs life is the day before the pig is weaned. Therefore, that is when you have to vaccinate. He also said that good injections are crucial.

In various studies that compared pigs who had not been vaccinated for PCV2, one dose and two-dose programmes, Dr Thacker concluded that:

• two-dose vaccination protected pigs until the end of the finisher phase
• one-dose programmes did not prevent viraemia in the finisher phase, and
• one-dose pigs had a lower average daily gain from 19 weeks through market age than those on the two-dose programme.

Dr Rick Schlueter, senior technical services specialist for ISPAH, concluded the series of conferences by talking about the Circumvent PCV M vaccine, a new PCV2 and Mhp combination vaccination. The vaccine is an aid in preventing viraemia as well as reducing the shedding of PCV2. It also aids in the control of mycoplasma.

He said that circovirus has always been there, but it is the type 2B that has created the challenge. Fortunately, vaccination does work against PCV2.

The new vaccine combined two existing vaccines, Myco Silencer ONCE and Circumvent. There is no interference between the two antigens against PCV2 and Mycoplasma hyopneumoniae. The vaccines bottle label was changed so as not confuse it with the other vaccines.

The results of studies with Circumvent PCV M showed that viraemia was reduced 82 per cent, nasal shed improved 80 per cent, fecal shed improved 71 per cent and lymph nodes improved 98 per cent. There was also a 63 per cent reduction in mycoplasma lesions.

Further Reading

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Find out more information on the diseases mentioned in this article by clicking here.