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Taking a blood sample from a sow as part of the Health Lift programme being applied to Dutch herds.
on July 1, 2009

Infection checks lead to healthier herds

Five major types of pathogen are being monitored in a project that is already improving the health of breeding herds in the Netherlands

Improving the health status of a herd is an important issue. Not only does it mean healthier pigs resulting in higher output, it also cuts down their production cost by reducing medication use and losses. An ongoing project in Dutch breeding herds has made substantial improvements to their health through the adjustments implemented after effective monitoring combined with tailor-made advice from the veterinary specialist of the national animal health service and the farm veterinarian.

This project has the name Health Lift. It was started in 2005 by breeding organisation Topigs in association with the animal health service GD. The intention from the start was that it would come to a way to monitor the health of herds, in order to stimulate the enterprises to follow farm-adjusted advice leading to management changes. In this way an improvement in the herd's health status could be achieved. Apart from that, it makes easier the matching of health status between supplier and buyer. In the end it could even lead to the elimination of pathogens.

A key to the monitoring process is that 5 causative agents are examined as the sentinels in blood and/or faeces of sample pigs in these herds. We have checked samples every 4 months for antibodies against the PRRS virus, the pleuropneumonia agent Actinobacillus pleuropneumoniae, the enzootic pneumonia agent Mycoplasma. hyopneumoniae and the Salmonella species while there has also been an in-faeces check for the presence of Brachyspira hyodysenteriae and B. pilosicoli causative agents of swine dysentery.

These 5 so-called Lift infections have given us our basis for monitoring, but it should be remembered that all breeding farms in the Netherlands have already participated for years in the eradication programme for Aujeszky/pseudorabies and they belong to certification schemes guaranteeing they are free of the causative agents of progressive atrophic rhinitis (Pasteurella multocida DNT) and mange (Sarcoptes scabiae). Samples are taken in various age groups, starting with piglets at 9 weeks old and sows in their first or second parity. Further sampling relates to sows in the third parity or later, growing pigs 3-4 months old and grow-finish pigs 5-6 months of age.

Today, over 120 Topigs breeding farms in the Netherlands participate in this project. Originally it was voluntary, but since January 2008 it is mandatory. Monitoring data are accumulated in a database and evaluated every quarter. Additionally, a GD specialist visits the farms. Together with Topigs, the farmer, the farm's veterinarian and advisory experts, this specialist formulates a plan of action partially based on the results of the measurements. In this plan, management, internal and external biosecurity, vaccination and/or treatment programmes are discussed and the farms then receive farm-specific advice.

The ultimate target for this project is to increase the health status per herd by eliminating certain pathogens or reducing the infection rate. However, it also aims to provide a better match in health terms between the supplier of genetic material and the client. This is the first step towards a long-term goal of raising the level of health across all of Dutch pig production.

It cannot be a realistic objective nationally without persuading producers to change the way they have been thinking about the management of health. Until quite recently there seemed a general attitude among Dutch producers that their pig units simply had to live with health problems. But experiences in daily practice have given the leading operators the insight that it is possible to work on a higher level health-wise. For example, they could see how SPF breeding farms were able to achieve and maintain freedom from certain infections despite being in a dense area for pig population.

Good early results have come from the units participating in the health monitoring project. Soon after the first checks, a clear reduction started to appear in the clinical aspects of the 5 sentinel diseases. Changes in serology are not seen immediately, but some general trends in improvement of the serological pattern are already showing up.

Antibodies decrease

For some farms the health monitoring is working very positively which means that they have managed to become free of certain pathogens. Decreases have been observed in the percentage of units in which the sampling finds antibodies for PRRS virus, App or mycoplasma. There are also farms where the research and tailor-made approach have contributed towards making the clinical signs of the diseases disappear. Therefore it is not surprising that the farms that start with the project do not want to end their participation. It is obvious to them that the extra attention and time they have devoted to improving herd health has been paid back twice over fewer pigs need treatment and the performance results are better.

Successive blood samples show that the upward trend in the health of the participants continues. It is more difficult to detect in sows for the simple reason that older animals still will have antibodies. This means pigs can still rate a positive score at a blood test, even though they are not ill and they are not spreading the pathogen. On the other hand, the improvement is extremely evident when looking at gilts that are transported from the breeding farm to the multiplier.

Many gilts do not have antibodies for some of the pathogens, meaning they are free of these. Looking at the score for PRRS, we see a rise in non-suspicious gilt deliveries from 2% to more than 10%. For App, the score is about 20% free. The success rate is higher still for mycoplasma, with about 50% of animal flows showing no or hardly any antibodies. Results for the swine dysentery agent are very hopeful: it seems Dutch breeding farms have almost no problems with Brachyspira hyodysenteriae and B. pilosicoli.

With salmonella, the results show a variable effect. This is logical because most breeders deliver gilts of different age groups to multipliers, meaning that they have to get gilts out of a pen more than once. The stress this causes raises the chance of excretion and transfer of salmonella. Other activities related to pig breeding work also make it inevitable that there is transfer of contamination between pens.

The extra attention given to hygiene and the way of working on a breeding site can positively affect the prevalence of pathogens (as the example in the accompanying box  illustrates). Also, data from the GD national heath service show that breeding farms have fewer problems with streptococci than would be true for commercial grow-out sites, although it is unclear if this also means the farms have fewer piglets with streptococci problems.

Gilt vaccination

The fact that gilts have a better health status increases the importance of the level of health at the piglet production sites. Unfortunately we find gilts become contaminated after some time on the commercial farm. The answer to this is to secure a good diagnosis of the farm's resident infections with the help of blood and manure tests and, following the results, to put together a vaccination programme designed for its new gilts during their period of quarantine and adaptation.

The next step in the project starts in 2008. It is to begin certifying herds that they are free of certain pathogens. Similar projects are being established by Topigs in France, Belgium and Germany. Domestically, we know already that the initiative in health monitoring that started 3 years ago has led to a new way of approaching health in the Dutch industry. Nowadays the monitoring approach has been adopted by others such as feed companies, consultants and veterinarians. The producers themselves are also progressively more occupied in bringing the health of pig production to a higher level, mainly by adjustments in management.

Of course, everyone profits from this approach. The health lift not only reduces infections, it also provides better food safety, a reduced use of antibiotics and improvements in animal welfare. All these are good for the image of the pig sector so they stimulate the sales of pigmeat. They also provide better production economies. What is more, having healthier pigs ensures better working conditions and more job satisfaction for the stockpeople.PIGI

0805PIGinfectionchart
This shows an example from the Dutch scheme, for the percentage of animals testing positive for any of 4 Lift infections at each examination. So 59% of the pigs here gave a positive result for PRRS at the first test, for example, dropping to 53% at the fourth test.
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