Rebecca DeMederios (Animal Science), Kyle Lunetta (Building and Construction Technology), Holly Sullivan (Animal Science), Alan-Michael Turner (Turfgrass Science and Management)
“A warning about Salmonella in eggs was issued today after two outbreaks of food poisoning, which have already claimed one life” (Daily Mail News, 2015). This past fall in the southeast and northwest of England, a Salmonella outbreak swept through, resulting in over 150 reported cases, and one death. Salmonella has become synonymous with eggs, and for good reason. “The Centers for Disease Control and Prevention estimates that over 1 million people in the U.S. contract Salmonella each year, and that an average of 20,000 hospitalizations and almost 400 deaths occur from Salmonella poisoning” (Marler Clark, 2016). It is for this reason that we must be vigilant regarding our egg handling practices, especially in free-range systems where the risk of salmonella exposure is significantly higher.
In today’s food economy, companies use labels such as ‘free-range’, ‘organic’, and ‘cage-free’ to sell products at higher prices to a new generation of consumers, toting that they implement more humane practices with the animals, and result in the production of a “healthier” product. But how much of this is the truth? Are free-range eggs truly a healthier option for consumers, or is it just a gimmick to sell more eggs at increased prices? Over the past five years, Australia has been shifting its egg production market from conventional cage systems to free-range systems (Egg Farming in Australia: Market Research Report, 2016). By March 13th 2015, Queensland Australia reported 1,895 cases of Salmonella (a record breaking high) since the start of that calendar year, with Salmonella cases totaling more than 10,000 annually (Davey, 2015). According to Peter Collignon, an infectious disease doctor and microbiologist with the Australian National University, around 75% of the rising Salmonella cases reported in Australia were a direct result of consuming and handling raw eggs (Davey, 2015).
It has been well documented that the type of housing facilities hens live in affect the microbial count of pathogens present on the surface of the eggs that they produce. The overall consensus of the research conducted on this topic states that the eggs produced in conventional cage systems are the “cleanest”, or most microbe free, and are therefore far less likely to have an impact on human health. Eggs produced in free-range systems tend to have higher counts of microbial growth on the shell surface, including specific strains of Salmonella and E. coli, among other harmful pathogens (Jones et al., 2014). According to the Human Society of the United States, “Salmonella poisoning is the most commonly diagnosed foodborne bacterial illness in the United States, costs the country billions, and remains the leading cause of food-related death” (2011). Because Salmonella is so dangerous and prevalent, decreasing the incidence of it should be a priority for producers.
The eggs coming from free-range production systems have a much higher incidence of microbial contamination than that of eggs coming from conventional cage production systems. The differences in management practices between free-range and conventional cage systems cause a large part of this disparity between eggshell microbial counts according to Jones and colleagues (2014). It has been found that in free-range systems, hens lay eggs on the ground or floor of their enclosures when not provided with enough nesting boxes per hen and when eggs are collected infrequently (Jones et al. 2014, p. 549). These “floor eggs” have the largest opportunity of exposure to microorganisms (Jones et al. 2014, p. 549). Floor eggs were consistently found to have the highest number of microbes present on their shells, increasing the concern of potential health risks (Jones et al., 2014, p. 549).
Free-range eggs have a higher likelihood of exposure to hazardous microbes such as Salmonella and E. coli due to lack of management practices within these facilities. This poses a risk to human health, as the chance of being exposed to Salmonella and E. coli is more likely in free-range systems. Salmonella is a type of food poisoning that consumers can obtain from handling contaminated eggs, from unwashed hands of an infected handler, or through fecal contamination. Salmonella can last on a surface for short periods of time, about 1-4 hours (“National Health Service UK”, 2015). On the other hand, E. coli can survive on a surface (depending on the material) for 24 hours or longer. A handler that does not collect frequently increases the probability of floor eggs, which can come into contact with these residing pathogens. Consequently, these handlers increase their own risk of infection, as well as the consumers’. Egg washing, although it is a protective measure, cannot completely eliminate this contamination, so E.coli and Salmonella still have the potential to spread to the general population. Biosecurity, procedures intended to protect humans and/or animals against disease or harmful biological agents (“Merriam-Webster”, n.d.), is critical to prevent the initial introduction of Salmonella and other pathogens to the farm. Limiting the hens’ exposure to Salmonella will reduce the potential introduction of this organism into the flock, and transmitting it among pre-existing and newly existing populations after cleaning and disinfection (Holt et al., 2011). Not only is the exposure of Salmonella and E.coli to the eggs problematic, but the potential of hens becoming infected is a problem as well. Hens have a greater chance of picking up these harmful microbes through exposure, increasing the likelihood of contamination of the eggshell. This increased risk of contamination without corrected management practices directly increases the risk of potential hazards, such as Salmonella and E. coli to human health. Without implementing these changes, exposure of hens to these potential health hazards in free-range systems is far more likely to spread to the egg production handlers, and eventually to the consumers.
Free-range production systems produce a far “dirtier” product than that of conventional cage systems. The eggs from free-range systems have much higher microbial counts on their shells than eggs from conventional cage systems, leading to a much higher risk of disease for not only the consumers, but also the workers that handle these eggs. Sophie Dwyer, the Australian government state health department’s health protection unit executive director, stated that the “dirty” eggs (the ones that have come in contact with fecal material) are more hazardous to consumers and handlers (Davey, 2015).
This leads to an increased risk of exposure to Salmonella and other harmful pathogens for both the consumers and the employees of these laying facilities who come in contact with these eggs. Salmonella was present on 2.36% of free-range eggshells, whereas it was detected on 0% the shells of conventional cage eggs (Parisi et. al, 2015, p. 164). The differences in production management between conventional cage systems and free-range systems, especially the varied cleaning practices between them, causes this disparity in the microbial counts on the eggs (Parisi et. al, 2015, p. 164). Management and upkeep of free-range systems needs improvement and regulation in order to combat these microbial eggshell counts.
The environment of free-range production systems is a major contributing factor to these higher microbial counts, as it is the actual source of contamination. Increased dust levels within free-range facilities directly correspond with increased levels of aerobic microorganisms, which add to higher microbial counts on free-range eggs versus conventional cage eggs (Jones, et al. 2014, p. 546). This poses a greater health risk to the workers handling the eggs at these free-range laying facilities, as well as to the consumers that purchase the eggs. By collecting and handling the eggs with higher microbial counts, the workers are coming in direct contact with Salmonella and other harmful pathogens, increasing their risk of falling ill. Consumers, especially young children, the elderly, and anyone with a compromised immune system, also have an increased risk of becoming ill when exposed to these pathogens. Addressing the causes of higher microbial counts present on free-range eggs will protect the health of the workers at these laying facilities as well as the consumers. Eggs laid in free-range systems have an increased risk for microbial contamination, which poses a risk to human health, necessitating more nesting boxes per hen, increased collection frequency of the eggs, and more standardized cleaning practices to reduce dust levels.
The variance of management practices in free-range systems is one of the biggest factors in microbial contamination of eggshells. Free-range systems lack the proper number of nest boxes per hen, which results in eggs laid on the floor of the facility, rather than in nest boxes. This issue was addressed by Jones, et. al (2014), stating that free-range eggs have the highest number of total aerobes, “microorganisms that grow in the presence of air or require oxygen for growth” (“Merriam-Webster”, n.d.), compared to any other type of egg production system. On the other hand, the nest boxes showed much lower levels of aerobes and one of the lowest levels of coliforms, “of, relating to, or being gram-negative rod-shaped bacteria (as E. coli) normally present in the intestine” (“Merriam-Webster”, n.d.) out of any egg surface across all three methods of production (Jones, et. al 2014, p. 547). Based on this information, a simple solution would be to introduce more nest boxes into free-range systems in order to decrease the risk of microbial contamination.
Not only would more nest boxes decrease the incidence of microbial contamination, but increasing the frequency of egg collection would help do this as well. Eggs produced in conventional cage settings are laid in an environment with some of the lowest measurements of both total aerobes and coliforms, according to Jones et. al. (2014) data on swab testing in egg production systems, making more frequent egg collection less important. Free-range systems, however, are much more likely to produce contaminated eggs, especially when the eggs are laid on the floor. Parisi et al. (2015) found levels of microorganisms up to 90% higher in free-range systems as a whole, but eggs laid on the floors of these systems are at the greatest risk. These eggs are the most likely to become contaminated, especially if they are not collected in a timely manner.
Dust levels vary greatly from conventional to free-range systems, causing a significant difference in the amount of airborne microorganisms and bacteria on the shell, according to Huneau-Salaun et al. 2010. In free-range systems, a substrate is added to the environment in order to give the hens a place to dust bathe and scratch. The addition of this substrate, although beneficial for the chickens’ welfare, is a major problem in the contamination of the eggshell surface in these systems. The average aerobe amounts on eggshells in aviary systems was 4.86 log CFU/eggshell and conventional cages measured at 4.40 log CFU/eggshell (Huneau-Salaun et al. 2010, p. 166). This problem becomes even worse as the laying period goes on, as it is difficult to clean the systems during the laying period without disturbing the hens (Huneau-Salaun et al. 2010, p. 167). This means that eggs laid at the end of the production period have a much greater chance of coming into contact with airborne microorganisms. Since conventional cages lack the need for a substrate due to the fact that they have wire cage bottoms, they have much lower levels of airborne dust and microorganisms throughout the laying period, resulting in less contaminated eggs. The management practices within free-range facilities need improvement, with the ultimate goal of creating a cleaner environment in the facilities so that the eggs produced within these facilities have less microbial contamination, and therefore pose a decreased risk to human health.
Currently, the microbial contamination of eggs laid in free-range systems is much higher than eggs from conventional cage systems. Improving the management of free-range production systems can better reduce the risks to human health. Free-range eggs are potentially exposed to additional biosecurity risks due to disease spread by both animals and airborne transmission. This results in diseases such as avian influenza, coccidiosis and pathogens responsible for food poisoning, like Salmonella, which occur at a higher frequency in poorly managed free-range poultry farms (“The Poultry Site”, 2016). Caged systems have increased labor demands due to the intensive standardized cleaning practices that maintain layer production, while the open environment of free-range systems requires less labor to maintain cleanliness. If management can be improved by increasing the collection frequency of the eggs and implementing more thorough cleaning practices, microbial contamination of the eggshells can be further minimized, making the eggs safer for handling and consumption.
Given that more stringent, labor-intensive management practices would increase the cost of free-range eggs, it would face some consumer opposition, despite being the safer option. The food market today provides the healthiest of foods for the most expensive prices. Caged eggs cost 43 cents/100g, while free-range are priced at 93 cents/100g (Walls-Thumma, 2011). This gives an average cost of $1.36 per dozen for caged eggs while free-range eggs average $3.99 per dozen (Walls-Thumma, 2011). With the cost of free-range eggs already so high, consumers who are not willing to pay for more expensive eggs would not support increasing management practices, even if it would potentially benefit their health. The more time spent managing free-range systems will inevitably cost the producer more, creating a more expensive product. However, this will provide healthier chickens, resulting in healthier products for consumers. Consumers that are already willing to spend $3.99 per dozen for free-range eggs will pay more for the same product if it is safer and will decrease the spread of harmful pathogens.
Implementing regulations and guidelines for free-range systems will improve the quality of egg laying conditions within these facilities. More standardized cleaning practices will help to alleviate dust levels that exacerbate the accumulation of microbes on eggshells. Although these regulations seem fairly simple to implement, some facilities are unwilling to spend the extra money it will take to update their caging systems. Free-range systems would benefit most from government-implemented guidelines for their egg production facilities. It would ensure the proper maintenance and care of egg collection and processing, in order to reduce the risk for human illness due to microbial contamination. The consumer will see the effects these regulations will cause the facilities economically, reflected as an increase in the price for eggs. Farmers will have to purchase the supplies and equipment necessary to bring their facilities up to these new standards, and as a result of these extra costs, the cost of eggs may go up. The guarantee of not contracting potential illnesses, such as Salmonella, from the eggs that they purchase is obviously in the consumer’s best interest, and well-worth the extra money.
We conclude that improving the management practices of free-range systems will decrease the incidences of microbial contamination of these eggs, resulting in a safer and healthier product. Through increasing the number of nesting boxes per hen, increasing the collection frequency of the eggs, and having more standardized regulations and guidelines regarding cleaning and management practices for free-range production systems, we can reduce the risk of microbial contamination of the eggs. According to government regulations in the United Kingdom, pasture management practices, including avoiding muddy conditions within the pasture, help to reduce the risk of infecting hens with disease carrying pathogens (“Poultry farming: welfare regulations”, June 13, 2013). In addition, free-range systems are required to provide the hens with protection from the elements, predators and other health risks (“Poultry farming: welfare regulations”, June 13, 2013). These management practices have proven attainable and effective within the United Kingdom, therefore the United States government would benefit from implementing these practices within free-range housing systems. With the addition of these management regulations, free-range systems will provide a healthier product for consumers. Producers should consider the health of the consumer their number one priority. These practices, when mandated and implemented by the government, will help to ensure the healthy upbringing of families throughout the country.
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