Abstract
Salmonella Enteritidis (SE) has been the most common Salmonella serotype associated with foodborne infections in the last several years. Dietary applications of yeast-based preparations in feed have shown to reduce Salmonella colonization in chickens augmenting SE control strategies. This study was conducted to evaluate the effects of a mannan-rich yeast cell wall-derived preparation (Actigen®) administered in feed at a rate of 400 g/ton on SE colonization in the cecum and internal organs of commercial layer chickens. Sixteen week-old layer pullets were orally challenged with a selected nalidixic acid resistant SE strain at a dose of 1.7×10^9 colony forming units (CFU) per bird. SE colonization was assessed by evaluating isolation rates from ovary and pooled liver/spleen samples as well as enumeration of SE in cecal pouches one week post-challenge. Recovery rates of SE from the ovaries of directly challenged birds receiving Actigen® were significantly lower (P <0.02) than those in directly challenged birds fed an unsupplemented control diet. Recovery rates of SE from pooled liver/spleen samples were not significantly different between Actigen®-treated pullets and controls (P = 0.22). Using direct plate count methods, cecal SE concentrations were 1 log10 lower (P <0.001) in challenged pullets in the Actigen®-supplemented group than in the challenged controls. The SE concentration distributions in the ceca were similar in groups testing positive and groups testing negative for SE in the ovaries and liver/spleens tissues. As a result, SE concentrations in the ceca could not be directly related to the occurrence or prevalence of SE in these tissues. In conclusion, Actigen® supplementation appears to decrease the prevalence of SE in ovarian tissue and concentrations of SE in cecal contents and may be useful as a tool for reducing the risk of eggshell contamination and transovarian transmission of SE in eggs.
Highlights
A recent report of the Foodborne Diseases Active Surveillance Network has stated that Salmonella continues to be the second most common infection in the United States, and that Salmonella Enteritidis (SE) is the most common serotype [1]
Birds were managed as has been prescribed by the Guide for the Care and Use of Agricultural Animals in Research and Teaching [15] with the study protocol approved by the Institutional Animal Care and Use Committee (IACUC) and the Institutional Biosafety Committee (IBC) of Iowa State University (ISU)
The relative number of directly challenged birds testing positive for Salmonella in ovary tissue was significantly lower (P < 0.02) in birds receiving the Actigen1-supplemented diet compared to controls (Table 1)
Summary
A recent report of the Foodborne Diseases Active Surveillance Network has stated that Salmonella continues to be the second most common infection in the United States, and that Salmonella Enteritidis (SE) is the most common serotype [1]. The incidence of human infections with SE has not declined in over 10 years [1, 3]. Some decline in serotype Typhimurium observed during the same period was thought to be associated with the use of modified live Salmonella vaccines, which are made of Salmonella Typhimurium [4]. In the United Kingdom, the use of modified live SE auxotrophic vaccine was followed by a decrease in human SE infections [5]. Even with the available modified live vaccines, Salmonella infections still represent a major problem in the United States. Other strategies that reduce colonization of layers and breeders are needed to augment available vaccines and management practices to achieve further reductions of Salmonella in eggs and poultry meat [6]
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