Dietary supplementation of a microencapsulated essential oil-organic acid blend with and without a protease affects performance, nutrient accretion, cecal microbiota, and circulatory biomarker concentrations in male broiler chickens

Abstract

The objective of the present study was to investigate the effects of supplementation of a combination of a microencapsulated essential oil-organic acid (EO-OA) blend in diets of broiler chickens in absence or presence of an exogenous protease on performance and serum biomarker concentrations indicating small intestinal mucosal integrity. In a 42-days feeding trial, 800 male Cobb broiler chickens were divided into 8 treatments (10 replicates/treatment, n = 10 per replicate). The dietary treatments, formulated by supplementing the EO-OA and the protease enzyme to the basal diet, were, therefore, control(C), EO-OA 150 mg/kg diet (T1), EO-OA 300 mg/kg diet (T2), EO-OA 300 mg/kg diet up to 28 d followed by 3000 mg/kg diet till harvest (T3), C + protease 125 mg/kg diet (T4), T1 + protease 125 mg/kg diet (T5), T2 + protease 125 mg/kg diet(T6), T3 + protease 125 mg/kg diet (T7). The objective of adding the EO-OA at 3000 mg/kg diet in the T3 and T7 groups during the finishing stage was to ascertain if at a plethoric level of supplementation, the EO-OA could provide additional benefits when broiler chickens are exposed to several environmental and physiological stressor stimuli. EO-OA and protease had insignificant effect on body weight and feed conversion ratio. Protease alone increased carcass fat accretion during 14 - 42 d (P = 0.05). Serum D-lactate decreased when EO-OA in diet increased (P = 0.017) at 14 d. Irrespective of the dietary EO-OA level, serum D-lactate at 42 d decreased in the birds fed with the protease supplemented diets (main effect protease P = 0.025). Clostridium perfringens in caecal digesta at 42 d decreased due to protease supplementation (P = 0.049). Numbers of both Escherichia coli and Campylobacter jejuni in cecal digesta decreased by dietary EO-OA (P = 0.0001). Protease supplementation tended to decreased numbers of E. coli (P = 0.053) while significantly decreasing that of C. jejuni (P = 0.043). In this study EO-OA, with or without the protease, showed several beneficial effects which included reduction of potential pathogens in caeca, and a better nutrient accretion. The findings also revealed the possibility of modulating the intestinal microbiota through application of exogenous protease. The EO-OA and protease combinations may, therefore, be explored as an effective tool for growth promotion of broiler chickens in the post-antibiotic era.