Finisher housing cleaning and disinfecting are central to Salmonella control

In the third and concluding feature on the Defra-funded R8 project, which is researching effective Salmonella control, we explore the study’s focus on cleaning and disinfection (C&D), with particular emphasis on finisher housing

Dr Rob Davies of the Animal Health and Veterinary Laboratories Agency (AHVLA), the organisation commissioned to undertake the research at the centre of the R8 project, says the work is centred on a holistic approach to Salmonella control, and the role of C&D is assessed as part of one of the on-farm interventions.

He explains that Salmonella, unlike most pig disease agents, survives very well in external environments and can live for months, if not years, in the right situations.

“For that reason, any time pigs are moved, there’s a chance of introducing them to a contaminated environment,” he says. “It still presents a risk even if the pigs are already infected, as they could be introduced to a new strain.

“What we find on most farms is that the finisher housing has the least amount of attention paid to it in terms of C&D. Therefore, at the point at which pigs enter the buildings, they can be faced with a high Salmonella disease challenge.

“As a result, the intervention involves introducing a vigorous cleaning and disinfection programme into the finisher housing schedule, based on more effective products that are used in the poultry industry.”

BPEX welfare projects coordinator Georgina Crayford adds that producers often think that, once the pigs are older, they’re immune.

“Yet this is the stage when the most attention should be paid, as ultimately these pigs are nearest to the food chain,” she says. “We tend to find that unless the pigs are infected with monophasic Salmonella Typhimurium, they’re sub-clinical carrier animals. They don’t show any symptoms, however, when they undergo a stressful event, for example during transportation or lairage, the infected pigs shed Salmonella and it can infect their pen mates before they go on the line.”

Explaining the process, Miss Crayford says it’s quite a complex biological relationship.

“We know that if the animal is stressed, the Salmonella seem to thrive in the conditions created by the stress hormones, which means they multiply rapidly in the gut and are shed in faeces,” she adds. “Some studies have shown that the process through which the Salmonella reach an uninfected pig gut can be very fast. This poses a significant threat to the contamination of pig meat on the line.”

Dr Davies notes that this really stresses the importance of an effective C&D programme for finisher housing, although the specific cleaning detail hasn’t been clarified yet.

“We do know it will involve using a detergent sanitiser, including an antibacterial agent that will loosen the muck, as well as reduce bacteria before washing,” he says. “This will be followed by a disinfectant based on glutaraldehyde, which is the chemical we have found to be most effective in difficult-to-clean conditions, such as finisher housing.

“The best results come from using a team of trained staff and ensuring the concentration of disinfectant is correct for Salmonella; use DEFRA’s General Orders concentration, not the standard application rate.”

However, Dr Davies warns that the battle against Salmonella can’t rely on C&D on its own.

“On most units there’s a rodent population that acts as a Salmonella reservoir, so no matter how good the C&D, rodent control must also form part of the programme,” he says.

Trial underway to monitor effect of moving outdoor sites
One R8 trial already underway has been planned to monitor the effect of moving outdoor herds annually, as opposed to bi-annually.

“The main problem with outdoor pig production is the accumulation of Salmonella contamination and other parasites in the soil and surface water,” Dr Davies says. “Once moved onto a new site, farmers often find they have a ‘golden period’ when disease levels improve.

“We are hoping to show that, although it may appear a lot of work to move every year, it might pay for itself through reduced health problems and in terms of fertiliser value to the land.”

AHVLA and BPEX are still recruiting farms to take part in a C&D trial that will commence later this year. Farms need to have two all-in-all-out finisher houses and the aim of the trial is to show that C&D in finisher housing, as well as effective rodent control, has a positive effect on Salmonella as well as the economics of production. Benefits should include better growth rates, FCR and less overall disease. If you would like to take part contact Victor Andres by email at: victor.andres@ahvla.gsi.gov.uk

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