Frequently Asked Questions
Q. My herd has a high ZNCP Salmonella prevalence, what does this mean?
Q. But how has this happened, they haven’t been ill, my herd is healthy?
Q. Why does this matter, everyone knows pork should be cooked well?
Q. Why should we go to this trouble, the supermarkets are full of imported meat, what are other countries doing?
Q. My other herd has a low ZNCP Salmonella prevalence. That means it doesn’t have Salmonella so I don’t need to do anything do I?
Q. So my pigs have Salmonella, what can I do about it?
Q. What is Salmonella?
Q. Where does Salmonella come from?
Q. If it is in my herd, how can I control it?
Q. Won’t antibiotics work on Salmonella; it is a bacterium isn’t it?
Q. What about a vaccine then, surely that would work?
Q. I have heard that changing the feed can help. How is this?
Q. A liquid feeding system would be hugely expensive. How can I justify it?
Q. I have an outdoor herd how can I control salmonella?
Q. Why should I have to take action - what are abattoirs and retailers doing about Salmonella?
Q. If I take over an existing unit what ZNCP Salmonella prevalence will I be given?
Q. My herd has a high ZNCP Salmonella prevalence, what does this mean?
A. Your herd is infected with Salmonella. The ZNCP test looks for antibodies in a small piece of muscle removed from your pigs at slaughter. This shows that they have been infected and may still be infected by Salmonella when they are slaughtered.
Q. But how has this happened, they haven’t been ill, my herd is healthy?
A. Salmonella doesn’t usually make pigs ill. They can carry it in their guts and the carcase is contaminated and may make consumers ill.
Q. Why does this matter, everyone knows pork should be cooked well?
A. The government is committed to making sure food is safe and that means making sure the animals that produce it are free of infections that can make consumers ill. Every year there are cases of Salmonella in people from eating pigmeat and Salmonella infections can be fatal. Cooking meat thoroughly does kill Salmonella. However, there is still a risk of cross-contamination from raw pigmeat to non-cooked food items when there is a lack of understanding of basic hygiene and food is handled incorrectly. After Edwina Curry's statement about poultry being infected with Salmonella, the industry lost millions of pounds and the cattle industry was devastated by BSE. The pig industry is being pro-active and is working at all levels along the food chain to reduce food safety risks.
Q. Why should we go to this trouble, the supermarkets are full of imported meat, what are other countries doing?
A. The rest of Europe is doing the same. Denmark has run a similar scheme for nearly 10 years and their Salmonella contamination rate has halved. Germany, Sweden, and Ireland have a scheme running now and the rest of Europe will follow from 2006. The ZNCP scheme is fully compliant with EU requirements.
Q. My other herd has a low ZNCP Salmonella prevalence. That means it doesn’t have Salmonella so I don’t need to do anything do I?
A. Your pigs may still be infected. There are hundreds of different Salmonellas and the test only picks up the commonest ones, but these are the majority of Salmonellas that pigs are likely to have. You may still have low levels of the common types or the infection may be only in your younger pigs so the test will not pick it up in your finished pigs. The ZNCP scheme requires all units to have a Salmonella Control Plan and to regularly review their management with respect to Salmonella.
Q. So my pigs have Salmonella, what can I do about it?
A. In May 2008 you will have received a ZNCP folder including a self-assessment form and example of an action plan. All units must have an action plan and you would be well advised to talk this over with your vet. The ZNCP scheme also has a team of advisors with specialist knowledge about control of Salmonella who are available for you to call on. Each herd is different so you will need to use the self-assessment form to identify areas of farm management to include in an action plan and review the plan with your vet at least once each year. Free on-farm Salmonella visits are available to the the discretion of the Veterinary Laboratory Agency (VLA), Scottish Government Rural Directorate/SAC or DARDNI to come and take samples free of charge so you will know how widespread the infection is and this will help you to plan how to control it.
Q. What is Salmonella?
A. It is a bacterium, not a virus. There are hundreds of different types of Salmonella but only a small number of common ones. They live in the gut and can infect people who eat contaminated food causing diarrhoea, vomiting and dehydration. It is a common cause of “Holiday tummy”. In a few people the disease can be more serious, even fatal. It likes to live in moist warm conditions and is found at very high levels in the dung of pigs, other animals and people. It will survive for months in pig dung.
Q. Where does Salmonella come from?
A. Salmonella may be coming into your herd by purchased pigs, vehicles, other animals including pests and birds, or visitors but there are many other possibilities.
Q. If it is in my herd, how can I control it?
A. You need to keep numbers under control by thorough cleaning and disinfection and controlling pests. You can help your pigs resist infection by reducing stress especially by movements and mixing. Changing the type of feed has a very large effect on the pig’s resistance (see below). Conditions on each herd vary so much that you need to prepare an action plan to suit your own particular circumstances.
Q. Won’t antibiotics work on Salmonella; it is a bacterium isn’t it?
A. Antibiotics are not the answer. Many Salmonellas are resistant to antibiotics and using them may induce even more to become resistant. Antibiotics can also make matters worse, causing pigs to carry salmonellas for longer than they would do otherwise Anyway you can’t use antibiotics close to slaughter or they will persist in the carcase.
Q. What about a vaccine then, surely that would work?
A. There is no commercial vaccine suitable for pigs. There is one in USA but that is only for a type of Salmonella that isn’t a problem here. The cattle vaccine doesn’t work well in pigs. The only possibility is an emergency vaccine made from Salmonella from your own farm. This has not been widely tested and is no replacement for other measures such as proper cleaning, disinfection.
Q. I have heard that changing the feed can help. How is this?
A. The pig’s gut carries a huge number of different bacteria. Different feeds produce different conditions in the gut that favour different bacteria. Research in several countries has shown that coarse ground meal based on barley reduces Salmonella levels enormously compared with pellets, though food conversion and growth rates will suffer. The best of all is liquid feed, especially if it is allowed to ferment before the pigs eat it. The fermenting bacteria in the feed produce acid, which changes conditions in the pig’s stomach helping them to resist Salmonella.
Q. A liquid feeding system would be hugely expensive. How can I justify it?
A. Your food conversion and growth rates will improve compared with meal and you may be able to use alternative sources of feed ingredients such as whey or brewery byproducts. You should manage to recover the cost in a reasonable period but you will need to seek specialist advice. In one experimental farm the cost was recovered in 2 ½ years. More detailed information about the costs and performance benefits of liquid feeding systems and payback periods on investments are available from BPEX . To find out more information call 01908 844734 or go to www.bpex.org.uk
Q. I have an outdoor herd how can I control salmonella?
1. Outdoor Breeding Herds
A. The majority of commercial outdoor herds are breeding herds and control of exposure to Salmonella in such an environment is more difficult. However, the ZNCP Salmonella programme is based on monitoring exposure in finished pigs. If these are finished indoors then you can reduce salmonella levels by the methods outlined above.
2. Outdoor Rearing and Finishing Herds
A. It is much more difficult to control Salmonella in outdoor finishing herds and you will need specialist advice. You can reduce Salmonella levels by controlling wild birds and pests, by moving paddocks and disinfecting equipment. You can help the pigs resist Salmonella by changing their feed from pellets to coarse meal or liquid.
Q. Why should I have to take action - what are abattoirs and retailers doing about Salmonella?
A. Processors are paying the cost of collecting samples for testing under the ZNCP scheme and are applying Hazard Analysis (HACCP) procedures to reduce the risk of Salmonella contamination. They are also starting to count bacterial contamination levels on meat and surfaces.
Q. If I take over an existing unit what ZNCP Salmonella prevalence will I be given?
A. Holdings that are joining the farm assurance schemes for the first time will have four sample per month tested and build up a ZNCP prevalence. If you take over an existing unit with its pigs and keep the same holding number then you will normally continue with the same ZNCP prevalence history.