Reduction of Salmonella enterica Serovar Enteritidis Colonization in 20-Day-Old Broiler Chickens by the Plant-Derived Compounds trans -Cinnamaldehyde and Eugenol

The efficacies oftrans -cinnamaldehyde (TC) and eugenol (EG) for reducingSalmonella enterica serovar Enteritidis colonization in broiler chickens were investigated. In three experiments for each compound, 1-day-old chicks (n = 75/experiment) were randomly assigned to five treatment groups (n = 15/treatment group): negative control (-veS . Enteritidis, -ve TC, or EG), compound control (-veS . Enteritidis, +ve 0.75% [vol/wt] TC or 1% [vol/wt] EG), positive control (+veS . Enteritidis, -ve TC, or EG), low-dose treatment (+veS . Enteritidis, +ve 0.5% TC, or 0.75% EG), and high-dose treatment (+veS . Enteritidis, +ve 0.75% TC, or 1% EG). On day 0, birds were tested for the presence of any inherentSalmonella (n = 5/experiment). On day 8, birds were inoculated with ∼8.0 log10 CFUS . Enteritidis, and cecal colonization byS . Enteritidis was ascertained (n = 10 chicks/experiment) after 24 h (day 9). Six birds from each treatment group were euthanized on days 7 and 10 after inoculation, and cecalS . Enteritidis numbers were determined. TC at 0.5 or 0.75% and EG at 0.75 or 1% consistently reduced (P < 0.05)S . Enteritidis in the cecum (≥3 log10 CFU/g) after 10 days of infection in all experiments. Feed intake and body weight were not different for TC treatments (P > 0.05); however, EG supplementation led to significantly lower (P < 0.05) body weights. Follow-upin vitro experiments revealed that the subinhibitory concentrations (SICs, the concentrations that did not inhibitSalmonella growth) of TC and EG reduced the motility and invasive abilities ofS . Enteritidis and downregulated expression of the motility genesflhC andmotA and invasion geneshilA ,hilD , andinvF . The results suggest that supplementation with TC and EG through feed can reduceS . Enteritidis colonization in chickens.