Alternative Livestock Systems

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Do Alternative Livestock Production Systems Yield Safer Food?

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July 2013

Authors
: Cara Cherry, Peter Davies, John Deen, and Fernando Sampedro, College of Veterinary Medicine; University of Minnesota.

Summary of Findings
  • Food products from alternative livestock production systems are increasing in popularity among consumers.
  • Limited research exists examining differences in food safety between conventional and alternative animal production systems.
  • There appears to be no difference in rates of Campylobacter, Salmonella, and E. coli in animals raised in conventional or alternative systems.
  • Animals raised in outdoor environments have an increased exposure to parasites and environmental contaminants.   
Background

Food products from alternative livestock production systems are increasingly available to consumers. Alternative producers employ diverse practices (grass-fed, free-range, organic, pasture-based, etc.) that differ from mainstream commercial production methods.1 Typical characteristics of alternative production systems include less intensive production, minimal or no antibiotic uses, and access to the outdoors or pastures.2  These features are used to market meat, dairy, or egg products to consumers who may be seeking products from alternative systems. Purchasers of these products may perceive the food to be superior for varied reasons including: animal well-being, environmental sustainability, nutritional value, taste, food safety or simply aesthetics.3,4  Perceptions of animal welfare is one of the more powerful features differentiating alternative and mainstream livestock production.

Among some consumers, there is a belief that animals raised in alternative livestock systems experience improved welfare conditions and that their food products are safer. While animals may benefit from certain aspects of free-range or pasture-raised systems, there are food safety concerns that arise from these types of production systems. Farms that provide access to the outdoors can be harder to control from a hygiene standpoint, depending on their set up and stocking densities. Farm biosecurity involves preventative measures designed to reduce the introduction and spread of disease agents; high biosecurity levels are usually not feasible with outdoor production systems.4  Animals with contact to the outdoors have more behavioral freedom but are exposed to soil, wildlife, and pests. These exposures can be risk factors for animal health and food safety by exposing the animals to diseases and/or toxic residues.5

Specific Food Safety Risks Examined

Limited research exists on the differences in food safety between conventional and alternative animal production systems in the United States. Salmonella enterica, E. coli O157:H7, and Campylobacter are some of the common bacterial causes of food poisoning from food products of animal origin. Some research has been done on the differences in frequency of foodborne pathogens between the two systems.

Birds are more susceptible to Campylobacter bacteria when raised in an environment with poor hygiene, fed a poor diet, or under stress.6  Several European studies have shown that Campylobacter is more common in chickens with access to the outdoors than conventional confined chickens.4  However, U.S. studies revealed a high occurrence of Campylobacter in both organic and conventional chickens, with no significant difference between the two production types.3,4  At this time, there is no substantial evidence to suggest that the free-range environment presents a major source of or protection from Campylobacter contamination for poultry.7

Regarding Salmonella, several studies have found that pigs raised in alternative systems can have higher rates of Salmonella.8,9 Results of other studies have indicated that there is no difference in Salmonella levels in finishing pigs from mainstream conventional and organic production systems.4 Additional studies in broiler chickens and dairy cattle found no difference in Salmonella levels between alternatively and conventionally raised animals.4

As with Salmonella, there is limited information on the differences in E. coli O157:H7 prevalence in conventional and alternative livestock production systems. There is a similar presence of E. coli O157:H7 in dairy cattle raised in organic and conventional production systems. No information is available for beef production systems.4

Aside from bacteria, certain parasites are a concern in alternative production systems. Conventional swine production practices have drastically decreased the amount of Toxoplasma gondii and Trichinella spiralis contamination in pork.1 The outdoor access of alternative production systems could lead to a re-emergence of these parasitic infections due to soil exposure.4,5,8,9

Increased exposure to environmental contaminants is another concern that arises from access to the outdoors. Free-range laying hens can produce eggs with higher levels of dioxins than traditional caged hens if there is contamination in the environment.5 Dioxins are unwanted contaminants that are produced from a variety of industrial processes that cause a variety of toxic effects in humans and other vertebrates.10 Free-range chickens consume the soil, insects, and worms that can have increased levels of dioxin. Dioxin easily can be transferred to the egg yolk.5 Other environmental contaminants can end up in free-range eggs, including lead, mercury, and pesticides.4

Conclusions

Much is still unknown about the differences in food safety of the products from conventional and alternative livestock production systems. Though alternative production systems with access to the outdoors may provide animal welfare benefits, they may pose a health risk through the introduction of food safety hazards. At this time, not enough information is available to determine the compatibility of alternative livestock production systems and US food safety standards. The assumption that alternative production systems improve food safety remains unproven. The traditional methods used to protect food safety in conventional livestock systems may not work well in certain alternative production systems and different approaches may prove necessary. Given the increasing popularity of alternative food production systems, more research is needed to determine what risks exist for specific systems and how they can best be managed. Furthermore, increased awareness by the public and farmers is necessary.

References
  1. U.S. Department of Agriculture. (2007, August). Sustainable agriculture: definitions and terms. Accessed 08/06/2013.
  2. University of Minnesota Extension. (2013). About alternative and small-scale livestock systemsAccessed 08/06/2013.
  3. Hanning, I., Biswas, D., Herrera, P., Roesler, M., & Ricke, S.C. (2010). Prevalence and characterization of Campylobacter jejuni isolated from pasture flock poultry. Journal of Food Sciences, 75 (7), M496- M502.
  4. Kijlstra, A., Meerburg, B.G., & Bos, A.P. (2009). Food safety in free-range and organic livestock systems: risk management and responsibility. Journal of Food Protection, 72 (12), 2629-2637.
  5. Boyle, L.A. & O’Driscoll, K. (2011). Animal welfare: an essential component in food safety and quality. In J. Hoofar, K. Jordan, F. Butler, & R. Prugger (Eds.), Food chain integrity: a holistic approach to food traceability, safety, quality and authenticity (169-186). Cambridge, U.K.: Woodhead Publishing.
  6. Rostagno, M.H. (2009). Can stress in farm animals increase food safety risk? Foodborne Pathogens and Disease, 6 (7), 767-776.
  7. Colles, F.M., Jones, J.A., McCarthy, N.D., Sheppard, S.K., Cody, A.J., Dingle, K.E., Dawkins, M.S., & Maiden, M.C.J. (2008). Campylobacter infection of broiler chickens in a free-range environment. Environmental Microbiology, 10 (8), 2042-2050.
  8. Davies, P.R. (2011). Intensive swine production and pork safety. Foodborne Pathogens and Disease, 8 (2), 189-201.
  9. Van Loo, E.J., Alali, W., & Ricke, S.C. (2012). Food safety and organic meats. Annual Reviews Food Science and Technology, 3, 203-225.
  10. Schecter, A., Birnbaum L., Ryan, J.J., Constable, J.D. (2006). Dioxins: an overview. Environmental Research, 101 (3), 419-428.  
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