The aim of the study was to evaluate the dietary supplementation with a microencapsulated blend of thymol and organic acids (mTOA) in broilers exposed to a necrotic enteritis (NE) challenge with Eimeria and Clostridium perfringens (CP). Two consecutive trials were conducted with day-old male chicks (Cobb500), vaccinated for coccidiosis (COCCIVAC®-B52), divided in floor pens (50 birds/pen) and assigned to dietary groups. In trial #1 (3,000 birds), groups were (12 pens each): unchallenged control (NEG), basal diet; positive control (POS), basal diet; and three groups fed basal diets supplemented with mTOA at either 100, 200 or 300 g/MT of feed (T100, T200, T300, respectively). In trial #2 (2,000 birds), groups were (10 pens each): CTR group, basal diet; BMD group, basal diet with 55 ppm of bacitracin; T200, basal diet supplemented with 200 g/MT of mTOA. All the animals except NEG group in trial #1 were orally challenged with E. maxima (5,000 oocysts) at day 14 and with a CP strain (field NE isolate, α and netB toxin positive, 108 CFU) at day 19, 20, 21. Both trials lasted 42 days with small intestine lesions scored at d21 (3 chicks/pen) and growth performance recorded throughout the studies. Data were analyzed with ANOVA and differences considered significant at P<0.05. In trial #1, during the challenge (d14-28), FCR was higher in POS 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 T100, T200, T300, respectively; P<0.0001). Overall (d042), the FCR value for POS group (1.75) was significantly higher than NEG group (1.61) and all the treated groups had FCR values comparable to NEG, unchallenged (1.66, 1.65, 1.63 for T100, T200, T300, respectively; P<0.0001). Treated groups showed reduced small intestine lesion score and lower overall mortality due to NE compared to POS control (P<0.0001). In trial #2, during the challenge (d14-28), BMD improved weight gain and FCR compared to CTR, while T200 showed intermediate improved values (P<0.01). In the overall period, FCR was significantly reduced in BMD (1.68) and in T200 (1.77) compared to CTR (1.84), (P<0.0001). Compared to CTR, total mortality, mortality due to NE and small intestine lesion scores were reduced by both BMD and T200 (P<0.01). To conclude, the microencapsulated blend of thymol and organic acids used in this study can be a dietary tool to control NE in broilers by improving growth performance and reducing intestinal lesions.
Discover More: Tugnoli et al. (2023). 23rd European Symposium on Poultry Nutrition (ESPN) 2023