Effects of a diet supplemented with a blend of protected organic acids and essential oils on growth performance and cecal microbiota composition in broilers

Organic acids (OAs) and essential oils (EOs) have several positive effects on the gut microbiota of broilers. In this study, we aimed to determine the efficacy of a blend of protected OAs and EOs [P(OA+EO)] on the growth performance and cecal microbiota of broiler chickens. A total of 160 Ross 308 broiler chickens, including 80 male and 80 female birds, all 1 day old, were randomly distributed between the control group (basal diet) and the treatment group [basal diet + 300 g/t P(OA+EO)] according to an 8-pen arrangement with 4 replicates of 20 birds. Body weight (BW), body weight gain (BWG), feed consumption (FC), feed conversion ratio (FCR), and European Production Efficiency Factor (EPEF) were calculated. Eight cecal samples were collected from each group. Microbiological analysis (Escherichia coli, Lactobacillus spp., Clostridium perfringens, Salmonella spp., and Eimeria spp.) and microbiome analysis (16S rRNA gene sequencing) were performed. As a result, BW, BWG, and EPEF were found to be higher in the P(OA+EO) than in the control group, while FC and FCR were found to be lower. The E. coli level was higher in the control group (5.1 x 105 CFU/g), while the Lactobacillus spp. level was higher in the P(OA+EO) group (3.6 x 106 CFU/g). Phyla of Firmicutes (88.2%-88.5%) and Bacteroidetes (5.6%-9.2%) were most common in both groups, while the levels of phylum Proteobacteria, which have a negative effect on growth performance, were 1.27% in the P(OA+EO) and 2.43% in the control group. The use of P(OA+EO) was found to be beneficial for maintaining levels of Faecalibacterium spp. and Lachnospiraceae-unclassified associated with improved BWG [22.48% in the P(OA+EO) group and 15.04% in the control group]. Our findings indicate that the P(OA+EO) treatment decreased intestinal pathogens and improved beneficial bacteria in the gut and broiler growth performance.