Thymol is a botanical well-known for its various biological properties (antimicrobial, anti-oxidant, antiinflammatory), while organic acids are widely used in poultry nutrition as antimicrobials. The aim of the study was to evaluate the effects of a microencapsulated blend of thymol and organic acids (mTOA) in broilers exposed to a necrotic enteritis (NE) challenge caused by Eimeria cocci and Clostridium perfringens (CP). A total of 3,000 day-old male chicks (Cobb500) were vaccinated for coccidiosis (COCCIVAC®-B52), divided in floor pens (50 chicks/pen) and assigned to 5 groups (12 pens/group): negative control (NEG), unchallenged, fed a basal diet; positive control (POS), challenged, fed a basal diet; and three groups challenged and fed a basal diet supplemented with mTOA at either 100, 200 or 300 g/MT of feed (T1, T2, T3, respectively). The challenge consisted of an oral inoculation with E. maxima (5,000 oocysts) at day 14 and with a CP strain isolated from clinical case of NE (α toxin and netB toxin positive, 108 CFU) for 3 days (d19, 20, and 21). The study lasted 42 days with small intestine lesions scored at d21 (3 chicks/pen) and growth performance recorded throughout the study. Data were analyzed with ANOVA and differences considered significant at P<0.05. From d14 to d28, during the challenge, POS group showed an FCR significantly higher than NEG group (1.89 vs 1.62) while the product inclusion improved FCR in a dose-dependent manner (1.78, 1.73, 1.61 for T1, T2, T3, respectively; P<0.0001). From d28 to d36, all the groups receiving mTOA had intermediate FCR values between NEG and POS groups (P=0.03). In the overall period, the FCR value for POS group (1.75) was significantly higher than NEG group (1.61) and all the treated groups FCR values were comparable to NEG, unchallenged (1.66, 1.65, 1.63 for T1, T2, T3, respectively; P<0.0001). Moreover, treated groups showed reduced small intestine lesion score at d21 (P<0.0001) and lower overall mortality due to NE compared to POS control (10 % for POS vs 4.3 %, 2.5%, 1% for T1, T2, T3, respectively, P<0.0001). To conclude, the microencapsulated blend of thymol and organic acids used in this study has the potential to contain loss of performance and lesions associated with NE challenge in broilers.
Discover More: Tugnoli et al. (2023). International Poultry Scientific Forum 2023