Mandating free range husbandry as a requirement for organic egg designation remains a prevailing sentiment within a segment of the organic community. The proponents maintain that such management practice ensures high hen welfare and enhanced wholesomeness of the egg. However, evidence from the field, especially in the European Union (EU), contradicts these assumptions. In many cases, hens allowed outdoor access were more subject to increased injury from predators and from flock mates, disease was more prevalent and generally more severe, and, as a result, higher mortality was routinely observed in these individuals compared with those raised indoors. The safety of eggs from free range hens is also questionable. Outdoor access compromises biosecurity efforts to curtail interaction of hens with rodents and wild birds, increasing the risk of flock Salmonella enterica serovar Enteritidis infection and consequent production of Salmonella-contaminated eggs. Even more serious, soil contaminated with dioxins and polychlorinated biphenyls, carcinogenic industrial by-products widespread in the environment, can be ingested by hens foraging outdoors. These compounds will subsequently be deposited into the egg yolks, many times at high levels, creating a serious food safety issue for the consuming public. Such findings provide evidence that hens exposed to a free-range environment may exhibit neither an enhanced welfare nor produce the safe wholesome egg that consumers expect.
Accurate and fast detection of harmful Salmonella is a major concern of food safety. Common Salmonella serotypes responsible for human associated foodborne outbreaks are S. Enteritidis, S. Hadar, S. Heidelberg, and S. Typhimurium are also commonly isolated from poultry. Serology is commonly used to monitor disease in poultry, therefore application of Salmonella serotype-specific test will have added value in Salmonella surveillance or monitoring vaccine efficacy. Recombinant flagellins were purified to be used as antigens in an ELISA. In this study, an ELISA was developed for the serological detection of S. Enteritidis. Once optimized, 500 ng of purified recombinant S. Enteritidis flagellin and a 1:64 dilution were determined to be optimal for testing sera. A negative baseline cutoff was calculated to be an optical density (OD) of 0.35. All sera from birds with history of S. Enteritidis exposure tested positive and all sera from chickens with no exposure tested negative to this Salmonella serotype. Current ELISA for serological detection of Salmonella suffers from cross reactivity inherent in lipopolysaccharide (LPS) or whole cell antigen based serological tests. This new ELISA eliminates common cross reactivity by focusing specifically on the flagellins of the Salmonella serotypes common in poultry and associated with foodborne outbreaks.