In-Feed Supplementation of trans -Cinnamaldehyde Reduces Layer-Chicken Egg-Borne Transmission of Salmonella enterica Serovar Enteritidis

Salmonella enterica serovar Enteritidis is a major foodborne pathogen in the United States, causing gastroenteritis in humans, primarily through consumption of contaminated eggs. Chickens are the reservoir host ofS . Enteritidis. In layer hens,S . Enteritidis colonizes the intestine and migrates to various organs, including the oviduct, leading to egg contamination. This study investigated the efficacy of in-feed supplementation withtrans -cinnamaldehyde (TC), a generally recognized as safe (GRAS) plant compound obtained from cinnamon, in reducingS . Enteritidis cecal colonization and systemic spread in layers. Additionally, the effect of TC onS . Enteritidis virulence factors critical for macrophage survival and oviduct colonization was investigatedin vitro . The consumer acceptability of eggs was also determined by a triangle test. Supplementation of TC in feed for 66 days at 1 or 1.5% (vol/wt) for 40- or 25-week-old layer chickens decreased the amounts ofS . Enteritidis on eggshell and in yolk (P < 0.001). Additionally,S . Enteritidis persistence in the cecum, liver, and oviduct in TC-supplemented birds was decreased compared to that in controls (P < 0.001). No significant differences in feed intake, body weight, or egg production in birds or in consumer acceptability of eggs were observed (P > 0.05).In vitro cell culture assays revealed that TC reducedS . Enteritidis adhesion to and invasion of primary chicken oviduct epithelial cells and reducedS . Enteritidis survival in chicken macrophages (P < 0.001). Follow-up gene expression analysis using real-time quantitative PCR (qPCR) showed that TC downregulated the expression ofS . Enteritidis virulence genes critical for chicken oviduct colonization (P < 0.001). The results suggest that TC may potentially be used as a feed additive to reduce egg-borne transmission ofS . Enteritidis.