Physiological changes in broiler chickens subjected to dietary ajwain (trachyspermum ammi l.) essential oil in encapsulated and conventional forms within a wheat-based diet

The aim of this study was to investigate the effects of different diet types, forms, and contents of ajwain essential oil (AEO) on various physiological characteristics of broiler chickens, including cell-mediated immunity responses, intestinal morphology, and microflora. A total of 1500 one-day-old male broiler chickens were allocated to different treatments based on a 2 × 3 × 2 factorial arrangement, considering diet types (corn and corn-wheat), contents of AEO (0, 150, and 300 mg/kg of diet), and forms of AEO (conventional and encapsulated). The results indicated that the broiler chickens fed the diet containing 150 ppm EO demonstrated reduced skin thickness in response to a 2,4-dinitrochlorobenzene challenge, 24 h after injection, compared to those receiving a diet without EO (P < 0.05). Increasing the EO content led to an increase in the villous height to crypt depth ratio in the jejunum of broiler chickens receiving 300 ppm EO (P < 0.05). Moreover, there was a slight improvement in the villous height to crypt depth ratio in the jejunum of broiler chickens fed the corn-wheat diet (P = 0.07). Broiler chickens fed the 300 ppm EO showed a lower total bacterial population compared to those fed the 150 ppm EO (P < 0.05). Finally, the use of EO at a content of 150 ppm improved cellular immune response, while EO at a content of 300 ppm improved the morphology and overall population of intestinal bacteria. Furthermore, the inclusion of wheat-corn diets exhibited enhanced morphological characteristics of the intestines. However, the forms of AEO did not exert any significant influence on the physiological traits.