Control of Salmonella in pig feed is worth the costs
Salmonella is still a rare finding at Finnish pig farms and in feeding stuffs for pigs. It is estimated that less than three slaughter pigs out of one thousand are carriers of Salmonella. Measures taken and carried on for decades to control and prevent Salmonella infections from feed, pigs and pig meat have been cost-effective. This is shown by the study on the risk of pig feed-borne Salmonella and costs of and benefits from the Salmonella control programme carried out by the Finnish Food Safety Authority Evira and Natural Resources Institute Finland (Luke).
Feeding stuffs and their quality play a significant role in the food supply chain. Results show that the risk management measures taken in the supply chain of feeding stuffs and pig meat affect prevalence of Salmonella up to consumer level. Control of pig feed-borne Salmonella and related measures to prevent spreading of Salmonella are cost-effective and beneficial for the society.
"This study is the first one in Finland concerning risk assessment of Salmonella and cost-effectiveness of Salmonella control starting already from imports of feed raw materials and production of feed. Results from this study can be put into practice particularly when assessing how current practices in Salmonella control function as well as need for change and possible consequences from changes made", says Professor Pirkko Tuominen, Head of Risk Assessment Research Unit at Evira.
Large study on pig-related supply chain
This study covered procurement of feed raw material, production and handling of feeding stuffs, feeding of pigs and production of pig meat. Prevalence of Salmonella in the production chain of pig feed and in pigs was estimated using a series of statistical models.
"In this model, even the maximum prevalence of Salmonella in pig feed and feed raw materials was estimated to be less than two per cent. This estimate also includes the commonly used source of protein, soya meal. Mean prevalence of Salmonella in pigs was 0.25 per cent, which was thus clearly lower than the maximum of one per cent set as a goal in Finland, although this estimate also included unidentified infections, says Research Professor Jukka Ranta, Senior Researcher at Evira.
Sources of Salmonella infections in pigs were also assessed using typing data of Salmonella strains isolated from pigs and wild animals. It was estimated that feeding stuffs explain an average of one third of Salmonella infections in slaughter pigs. However, an exact estimate is not possible, since there is substantial uncertainty in the proportion of other infection sources and since infections are rare.
Prevention of Salmonella is cost-efficient
The cost-benefit analysis of Salmonella control was made on basis of cost data from 2013 for both preventive measures of Salmonella and for costs caused by Salmonella findings. Costs from current Salmonella control measures were compared to an alternative where control and prevention of Salmonella would be less intensive than today and where no measures would be taken even if feed-borne Salmonella was detected. In this case, the number of Salmonella infections in animals and humans would increase. It was estimated that preventive costs related to imports of feeding stuffs, feed production and measures taken at pig farms would total to 1.8 - 3.0 million euros per year.
"Currently, costs from control and prevention of Salmonella as well as costs resulting from Salmonella-contaminated pig feeding stuffs and subsequent decontamination measures as well as outbreak of infections in humans totalled to about 4.1 - 5.4 million euros per year. In an alternative situation where there would be no control of feed-borne Salmonella, prevalence in pig feeding stuffs would be higher. This would result in an increase in Salmonella infections in pigs to up to 12 per cent. As for costs, this could mean an increase of up to 7-fold totalling to an average of about 34 million euros per year, says Research Professor Jarkko Niemi from Natural Resources Institute Finland (Luke)
Salmonella is one of the most serious food-borne illnesses in Finland
The model developed in this study was used to assess the proportion of Salmonella infections in humans in Finland originating from pig feeding stuffs.
It is estimated that about five per cent of 300 - 400 domestic Salmonella infections in Finns every year can be explained by pig feed. This estimate is partly based on the types of Salmonella bacteria isolated from those with a Salmonella infection.
Overall, two thousand human Salmonella infections are registered in Finland every year. In the calculation of costs from human Salmonella infections in Finland, the costs from acute illness as well as its sequelae were taken into account.
In their report, Risk Assessment Research Unit at Evira also reviewed the probability of feeding stuffs to spread Salmonella infections to pigs in Finland as well as the effects from the requirements in the current control programme on frequency of Salmonella infections. Natural Resources Institute Finland (Luke) reviewed on their part the costs from control of Salmonella to actors in feeding stuff business as well as benefits from this control observed as reduced costs related to decontamination of infections and costs from the illness.
For more detailed information on the assessment of Salmonella control, please see the study report
Please also see the peer-reviewed scientific publications:
Välttilä, V., Ranta, J., Rönnqvist, M., Tuominen, P.
Bayesian model for tracing Salmonella contamination in the pig feed chain. Food Microbiology 2017.
Rönnqvist, M., Välttilä, V., Ranta, J., Tuominen, P.
Salmonella risk to consumers via pork is related to the Salmonella prevalence in pig feed. Food Microbiology 2017.
More information about Salmonella (National Institute for Health and Welfare, in Finnish)
Research Professor Jukka Ranta, Senior Researcher, Risk Assessment Research Unit, tel. +358 40 489 3374
Pirkko Tuominen, Head of Risk Assessment Research Unit, tel. +358 400 211 624
Luke: Research Professor Jarkko Niemi, bioeconomy and environment, tel. +358 295326392