Effects of supplemental essential oil on growth performance, lipid metabolites and immunity, intestinal characteristics, microbiota and carcass traits in broilers

This study was conducted to investigate the potential of essential oil as growth promoting agents and as a potential alternative to antibiotic. A total of 240 day-old-Arbor Acres broilers were divided into 3 equal groups as follows: negative control (no essential oil or antibiotic), positive control or antibiotic (100 ppm oxytetracycline) and essential oil (125 ppm including essential oil derived from oregano, anis and citrus peel). The experiment was performed in 4 replicate pens, with 20 birds, and carried out for 42 days. Birds were given feed and water ad libitum. Feed/gain ratio was improved in the essential oil group during the entire experimental period and in antibiotic group during the 0-21 day period. Both antibiotic and essential oil supplementation increased the survival rate by approximately 10%, as compared to the negative control group. Serum levels of cholesterol were reduced by either the treatment with antibiotic or essential oil, while birds receiving essential oil supplementation had lower VLDL levels and higher total polyphenolic compounds and total flavonoids. Sheep red blood cells (SRBC) antibody titer and immunoglobulin G (IgG) concentration were unaffected by either antibiotic or essential oil supplementation. A decrease in the Newcastle disease antibody titer was observed in the antibiotic treatment. Intestinal pH values of the different intestinal parts (duodenum, jejunum and ileum) were unaffected by any treatment. Compared with the control group, concentrations of caeca total volatile fatty acids (VFA) decreased in birds fed with antibiotic. Ileum ammonia concentration was the lowest in birds fed with essential oil and antibiotic supplementation, and the highest in the control group. Total ileum microbiota counts were not affected by any treatment. Essential oil supplemented birds had longer duodenum villi, while jejunal and ileal villi heights as well as cryptal depth were similar among all groups. Breast muscles were more tender and thigh muscles were juicier for birds in the essential oil group, as compared to the control and antibiotic groups. The results showed that essential oil could be considered as a potential natural growth promoter, and may be used as an alternative to antibiotic. (C) 2012 Elsevier B.V. All rights reserved.