Microencapsulation of basil oil and its effect on replacement of antibiotic growth promoter, antioxidant status and gut functions of broilers

Abstract

The objectives of this work were 1) to study the preparation and characterization of microencapsulated basil oil (MBO), 2) to determine the stability of MBO against simulated gastrointestinal tract and storage 3) to investigate the antimicrobial and antioxidant properties of MBO and 4) to evaluate the supplementation of MBO on growth performance, antioxidant status, ileal digestibility and intestinal morphology in broiler chickens. The present work demonstrates the use of double-layered polymers (chitosan, CS and sodium alginate, SA) with opposite charges leading to a dual pH responsiveness. The double-layered microcapsule was studied on physicochemical characteristics, the swelling performance as well as the release efficiency and the antioxidant and antimicrobial stabilities under the storage. A total of 288 one - day - old female broilers (Ross 308) were randomly allocated into 4 groups (6 replicates of 12 birds), based on a completely randomized design. Dietary treatments were (i) basal diet (NC), (ii) basal diet with avilamycin at 10 ppm (PC), (iii) basal diet with free basil oil (FBO) at 500 ppm, and (iv) basal diet with MBO at 500 ppm, respectively. Fourier transform infrared (FTIR) and thermogravimetric analyses (TGA) proved successful loading of BO in CS-SA and improved its thermal stability. Swelling showed great performance, whereas CS-SA displayed the cumulative release of BO in gastric stage (63.3 ± 4.6%) and in intestinal stage (86.8 ± 4.4%), respectively. CS-SA retains the antioxidant and antimicrobial activities of BO under storage in addition to a great tolerance of acids, bile, trypsin, including the thermal conditions. MBO improved average daily gain (ADG), and feed conversion ratio (FCR) of broilers throughout the 42-d trial (P < 0.05). The broilers fed MBO diet exhibited a greater AID of crude protein (CP) and gross energy (GE) compared with those in other groups (P < 0.05). Lactobacillus spp. and E. coil populations were not affected by feeding dietary treatments. Both FBO and MBO had positive effects on jejunal villus height (VH), villus height to crypt depth ratio (VH:CD) and villus surface area (VSA) of broilers compared to NC and PC groups (P < 0.05). Superoxide dismutase (SOD) level in the duodenal mucosa of MBO group was significantly increased (P < 0.01), whereas malondialdehyde (MDA) level was significantly decreased (P < 0.01). The concept of double-layered polymer in microcapsule form could be considered as a promising driver of the BO efficiency, consequently MBO could be potentially used as a feed additive for improvement of intestinal integrity and nutrient utilization, leading to better performance.