Impact of Nanoencapsulated Rosemary Essential Oil as a Novel Feed Additive on Growth Performance, Nutrient Utilization, Carcass Traits, Meat Quality and Gene Expression of Broiler Chicken.

This study evaluated the effect of free and nanoencapsulated rosemary essential oil (REO) as an antibiotic alternative in broiler diets on growth performance, nutrient digestibility, carcass traits, meat quality and gene expression. Four hundred twenty day-old commercial broiler chicks (VENCOBB) were randomly allocated to seven dietary treatments, each having four replicates of fifteen chicks. The dietary treatments comprised control (CON) fed a basal diet only, AB (basal diet + 10 mg enramycin/kg), CS (basal diet + 150 mg chitosan nanoparticles/kg), REO and REO (basal diet + 100 mg and 200 mg free REO/kg, respectively), and REO and REO (basal diet + 100 mg and 200 mg nanoencapsulated REO/kg, respectively). Overall (7-42 d), REO showed the highest ( < 0.001) body weight gain (1899 g/bird) and CON had the lowest gain (1742 g/bird), while the CS, REO and REO groups had a similar gain, but lower than that of the AB and REO groups. Feed intake was not affected by dietary treatments. Overall, the feed efficiency increased ( = 0.001) by 8.47% in the REO group and 6.21% in the AB and REO groups compared with the CON. Supplementation of REO improved ( < 0.05) dry matter and crude protein digestibility, with the highest values in REO and REO. Ether extract, crude fiber, calcium and phosphorus digestibility values showed no difference among the groups. The dressing, breast, thigh % increased ( < 0.05) and abdominal fat % decreased ( < 0.001) more in the REO group than with other treatments and CON. In breast meat quality, water holding capacity and extract reserve volume increased ( < 0.05) while drip loss and cholesterol content decreased ( < 0.05) in REO and REO. No change was observed in the breast meat color among dietary treatments and CON. The REO and REO groups had reduced ( < 0.05) meat lipid peroxidation as depicted by the decreased levels of TBARS, free fatty acids and peroxide value compared to other treatments and CON. The expression of the Mucin 2, PepT1 and IL-10 genes was upregulated ( < 0.001) and TNF-α downregulated ( < 0.001) by dietary addition of REO particularly in the nanoencapsulated form compared with the CON. In conclusion, nanoencapsulated REO, especially at 200 mg/kg diet, showed promising results as an antibiotic alternative in improving the performance, nutrient digestibility, carcass traits, meat quality and upregulation of growth and anti-inflammatory genes.