AbstractThe objective of this experimental study was to investigate the effects of essential oils of oregano, laurel and their combination on growth performance, intestinal microbiota and intestinal morphology as replacers of antibiotic growth promoters, as well as on the antioxidant capacity and mineral content of breast and thigh meat. A total of 256 day-old broiler chickens were randomized into 4 groups with 4 replicates. Control group received a basal corn-soybean diet, whereas the other experimental groups received the basal diet plus 25 mg/kg oregano essential oil, 2.5 mg/kg laurel essential oil or their combination, respectively. Chickens had free access to water and feed. Body weight gain and feed to gain ratio was calculated for the total fattening period and mortality was daily recorded. Intestinal microbiota was enumerated by conventional techniques with selective agar media at the end of the trial at both ileum and caecum. Also, evaluation of intestinal morphology was carried out in small intestine and caecum. At the end of the trial, birds were slaughtered, their carcasses were processed and samples of breast and thigh meat were analyzed for moisture, fat and protein content. Total phenolic content was determined in feeds and breast and thigh meat in order to assess its antioxidant capacity. Mineral content of breast and thigh meat was evaluated by ICP-MS. The results of the trial showed that the group that received oregano or the mixture of oregano and laurel presented better BW and FCR and mortality compared to control group. Bacterial counts for the Lactobacilli and Bifidobacteria were higher in the experimental groups compared to the control group at both ileum and caecum, and total coliforms were lower in caecum in the experimental groups compared to control. Higher values for villus height were found for the oregano supplemented groups compared to control or laurel ones. Oregano supplemented groups showed higher antioxidant capacity of breast and thigh meat compared to control and laurel groups, however no changes in mineral content were noted among the different groups. In conclusion, oregano essential oil alone or as a mixture with laurel essential oil can be used to improve growth performance and gut health in broiler chickens.
Efficacy of Bacillus subtilis and bacitracin methylene disalicylate on growth performance, digestibility, blood metabolites, immunity, and intestinal microbiota after intramuscular inoculation with Escherichia coli in broilers
