Salmonellosis is a foodborne disease frequently transmitted with poultry products that causes gastroenteritis in humans. Alternatives to antibiotics demand is growing worldwide in order to control diseases and fight the antibiotic resistance issue. The aim of the study was to compare the effect of a microencapsulated thymolbased blend of botanicals (TBB) with commonly used in-feed antibiotics in broilers during a Salmonella Enteritidis challenge. Prior to the in vivo study, the susceptibility of the inoculum strain to a panel of antibiotics was evaluated using Sensititre™ plates. Tylosin and neomycin were chosen as the strain was resistant to the former and susceptible to the latter. A total of 500 day-old straight chicks (Ross 308) were placed in floor pens (50 chicks/pen) and assigned to 5 groups with 2 replicates each. The groups were all fed with basal diets, without supplementations (CTR) or supplemented with: tylosin at 25 g/MT (TYL); neomycin sulfate at 100 g/ MT (NEO); or TBB at inclusions of 500 g/MT (B500) and 1000 g/MT (B1000). All the pens were orally challenged at day 4 with the S. Enteritidis strain at 10^5 CFU/bird. At 7, 14, 21, and 35 days of life, ten animals from each pen were weighed and sacrificed in order to count Salmonella in ceca and determine its prevalence in the liver. Body weights and cecal counts were analyzed with ANOVA and differences considered significant at p < 0.05. Body weights remained stable until d35, when B1000 was significantly higher than all the other groups (+152 g compared to CTR). The trend of Salmonella counts in ceca for CTR, B500, and B1000 showed a peak at d14, followed by a progressive decrease until the bacteria at d35 were totally cleared. TYL had elevated counts throughout the experiment, concluding with the highest value among all groups (5.3 Log10 CFU/g; p < 0.0001). NEO showed low counts during the first three necropsies reaching the peak at d35 and being statistically higher than CTR, B500, and B1000 (2.3 Log10 CFU/g; p ≤ 0.0005). The same trend was observed in the percentage of Salmonella prevalence in liver: at d35 the prevalence in CTR and TBB-fed groups was null, whereas in TYL and NEO was 90% and 40% respectively. To conclude, the thymol-based blend of botanicals at the highest dose had a positive effect on the final body weight. Furthermore, the blend at both doses was able to completely clear S. Enteritidis in broilers, while conventional antibiotics were not effective.
Discover More: Giovagnoni et al. (2023). 23rd European Symposium on Poultry Nutrition (ESPN) 2023