This experiment investigated the effect of the compound of microencapsulated essential oils ( CMEOs ) on productive parameters, antioxidant status, meat quality, and humoral and cellular immune responses in broilers. In a completely randomized design, a total of 640 (mixed-sex) one-day-old Ross 308 broiler chickens were divided into 4 treatments with 10 replicates (16 chicks/replicate) for 42 days. Treatments were basal diet supplemented with CMEOs at levels of 0 (control), 300 (CMEOs-300), 600 (CMEOs-600), and 900 (CMEOs-900) mg/kg of diet. The CMEOs contain equal weight ratios of eucalyptus, oregano, rosemary, and thyme essential oils ( EOs ). The results showed that, compared to the control and other groups, the CMEOs-900 treatment increased (ANOVA and linear, P = 0.001) total body weight gain and decreased (ANOVA, P = 0.001; linear, P = 0.04) feed conversion ratio throughout the entire experimental period. The CMEOs-900 treatment increased (ANOVA and linear, P < 0.05) total antioxidant capacity and the enzyme activity of glutathione peroxidase, superoxide dismutase, and catalase in the serum of broilers, compared with the control and other treatments. Feeding CMEOs-900 increased (ANOVA and linear, P < 0.05) 2,2-diphenyl-1-picrylhydrazyl and 2,2ʹ-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt free radical-scavenging activities, as well as decreased (ANOVA and linear, and quadratic, P < 0.05) malondialdehyde levels in breast meat at various times of storage, and serum compared with the control and other groups. The group fed CMEOs-900 increased (ANOVA, P < 0.05) breast meat pH values and water-holding capacity at 7 and 14 days of storage compared to the control and other groups. Broilers fed CMEOs-900 showed a higher (ANOVA and linear, P < 0.05) immune response against phytohemagglutinin and 2,4-dinitrochlorobenzene challenge, antibody titers against Newcastle disease virus, total anti-sheep red blood cell titer, immunoglobulin M, immunoglobulin G, as well as lower (ANOVA and linear, P < 0.05) heterophil count, and heterophil-to-lymphocyte ratio compared to the control and other groups. In conclusion, supplementing CMEOs-900 in the broilers' diet improves productive parameters, cellular and humoral immune responses, antioxidant enzyme activity, meat quality, and oxidative stability.
Safari et al. (Fri,) studied this question.