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PCV2 Vaccines: Separating Fact from Fiction

by 5m Editor
17 February 2009, at 7:56am

UK - BPEX's PCV2 vaccine voucher scheme has given pig producers in England and Wales a unique opportunity to try one of the new PCV2 vaccines at a very low cost. Comparing sow and piglet vaccination against PCV2, Merial says that both have their place: the better option depends on the specific conditions on the farm.

Many have opted for sow vaccination, which was first to market and has been widely available for almost two years. As a result, there is a large amount of data, from on-farm use of sow vaccination in the UK and elsewhere in Europe, showing impressive reductions in mortality and increased weight gains in pigs of all ages from birth right through to slaughter.

More recently, piglet vaccines have become available and the uptake of these has also been impressive. There are several key factors involved in the decision- making process when deciding which vaccine type to use on any particular unit, which can be summarised as follows:

The type of unit – Sow vaccination has shown excellent results in all types of units. However, if weaners are purchased from a number of different sources where it is not possible to ensure that sows are vaccinated, then using a piglet vaccine on arrival will ensure all piglets are protected.

Time to results – Where a unit is experiencing an outbreak of PMWS and mortality has risen sharply, a piglet vaccine can give quicker results due to the shorter time period between administering the vaccine and the onset of disease. Under these circumstances, following advice from their vet, producers have the option of vaccinating piglets from unvaccinated sows with the aim of damping down the outbreak quickly. And at the same time, they can start to vaccinate sows with a sow vaccine to protect piglets from subsequent farrowings. Once these piglets reach weaning age, vaccination of weaners with the piglet vaccine may be discontinued.

Convenience - For many producers, the process of sow vaccination requires less time and effort compared with piglet vaccination, therefore saving on labour costs. Fewer injections are necessary to protect the herd, and there is less chance of self- injection accidents to staff. Vaccinating sows also allows more flexibility as the vaccination can take place over a longer time frame, allowing for scheduling vaccination in less busy times on the farm.

Cost – When considering the cost of a vaccine per piglet protected, a piglet vaccine costs considerably more than a sow vaccine. This excludes any labour costs and is a reflection not only on price per dose but also the total number of doses required. Under the BPEX scheme, producers in England and Wales have benefited from subsidised vaccine, which has largely hidden these cost differences. When the scheme comes to an end in the coming weeks, this difference in cost between the vaccines will become more apparent.

Why a sow vaccine for a piglet disease?

Until recently, many people have regarded PCV2 as the cause of diseases of the growing / finishing pig, such as PMWS and other PCV2 associated diseases. These lead to increases in mortality, wasting and reduced growth rates in pigs post-weaning and therefore these parameters have been the main criteria for judging vaccine efficacy. To date, there are no published peer-reviewed scientific papers directly comparing the efficacy of piglet versus sow vaccination. However, data from both UK and abroad demonstrates the effectiveness of all the licensed vaccines is impressive when measured against the parameters mentioned above. It is important to note that other production benefits can result from vaccination aside from post-weaning performance.

Feedback from the BPEX scheme in England and Wales, and also published scientific papers based on data from field studies throughout Europe, have shown that sow vaccination can lead to reproductive improvements in the sow herd, e.g. an extra 0.5 piglets weaned per litter, as well as improved conception rates (BPEX). Not only is this a significant benefit in improved efficiency and performance but it also underlines the fact that PCV2 can and does have a negative impact in the sow and supports the case for sow vaccination.

Widespread use of sow vaccination has also resulted in reductions in pre-weaning mortality and improved growth rates in the first few weeks of life.

The improvements in sow reproductive performance and pre-weaning performance of pigs from vaccinated dams underline the fact that to evaluate accurately the effectiveness of sow or piglet vaccine, one needs to consider the bigger picture and not just look at improvements in the post-weaning pig.

For example, to achieve the same increase in pig meat produced per sow per year as that achieved as a result of an increase of 0.5 pigs per litter reported by BPEX from sow vaccination, a farm would need to see a reduction of over 4 per cent in total mortality. This is out of reach for most farms as their current mortality levels in an endemic (or chronic) PMWS phase are relatively low compared to the peaks seen at the start of a PMWS outbreak (acute phase). To see the bigger picture, one needs to look at the total improvement achieved through the increased number of pigs weaned per sow per year as well as decreased mortality. When both are analysed on farms using sow vaccination, the improvements are spectacular.

“Late stage PMWS”

Following the emergence of PMWS in the late 1990s, the disease was seen to cause increased mortality and wasting of pigs shortly after weaning, at 6 to 8 weeks of age. More recently, the syndrome has been observed in older pigs of up to 16 weeks of age and, while mortality rates have not been as high as previously observed, they have remained higher than pre-PMWS levels. Some have argued that this so called “late stage PMWS” requires piglet vaccination to reduce mortality and improve performance in these older pigs, and that a sow vaccine would ‘run out’ before pigs reach this age.

However, the facts do not support this argument. Data from several million pigs throughout Europe demonstrates that sow vaccination reduced mortality and improved growth rates in all ages of growing pigs from birth right up to slaughter.

Good colostrum management

A good start to life has a critical impact on the performance of pigs throughout their growing life. This starts with good farrowing house management and adequate colostrum intake. To get the benefits of sow vaccination, it is particularly important new-born piglets receive sufficient colostrum. As a general rule 160 to 200 ml per piglet in the first 12 hours is sufficient. This is not just important for protection against PCV2 but other diseases such as neonatal E. coli, Erysipelas and atrophic rhinitis. If colostrum intake is suspected to be below this level, efforts should be adopted to improve this by split suckling, good cross fostering practices, ensuring optimum health status of the sows at farrowing (worm burden, body condition scoring) and good farrowing house management practices (e.g. temperature, water supply to the sows, good farrowing supervision, etc). If colostrum intake is an issue and cannot be improved, vaccination of piglets may be the preferred route.

In summary

There are a number of different factors to consider when deciding whether sow or piglet vaccination is most appropriate for any particular unit following a proper diagnosis by your vet. No matter which vaccine is used, it is important not to neglect other management factors such as hygiene and stocking rates and other diseases that may be present on the unit.

There is no single correct answer on the choice of PCV2 vaccines applicable to all farms. Both sow and piglet vaccines have their place depending upon the specifics of the unit concerned. It is important to recognise the benefits from vaccination can make a significant financial impact on improving the performance of not just the growing pig but also sows and gilts. In many instances, the payback can be in the region of 10 to 1 return on investment on the cost of vaccination.

If you would like to know more about the potential financial benefits you can get from PCV2 vaccination, get in touch for a free demonstration of Merial’s PCV2 Cost Benefit Calculator. This programme has been designed using performance data from published scientific papers, detailing the improvements in performance following vaccination and, by combining this with current feed prices and your own herd performance data, the model can give you an indication of the potential financial gains. If you would like to know more then please contact Ricardo Neto, Technical Advisor – Pigs, Merial Animal Health by calling the Merial Customer Support Centre on free phone 0800 592699.

Further Reading

- You can visit our PMWS page by clicking here.