Nano-protected form of rosemary essential oil has a positive influence on blood biochemistry parameters, haematological indices, immune-antioxidant status, intestinal microbiota and histomorphology of meat-type chickens.

This study aimed to investigate the potential of free and nanoprotected rosemary essential oil (REO) as an antibiotic alternative in blood biochemistry, hematology, immune-antioxidant status, intestinal microbiology, and histomorphology of broilers. A total of 420 1-wk-old broiler chicks (Cobb) were randomly allotted into 7 treatments, each having 4 replicates of 15 chicks. The first group served as control received basal diet, while the second group was fed a basal diet plus 100 mg/kg enramycin and third group basal diet plus 150 mg/kg chitosan nanoparticles (CNPs). The fourth and fifth groups received diets supplemented with 100 mg and 200 mg free REO (F-REO)/kg diet. The sixth and seventh groups were supplemented with 100 mg and 200 mg nanoprotected REO (N-REO)/kg diet. Results revealed that supplementing nanoprotected REO significantly (P < 0.05) decreased the levels of blood cholesterol and low-density lipoproteins (LDL) compared to control and enramycin groups. The kidney and liver function parameters were not altered by adding free or nanoprotected REO to the diet. Both levels of nanoprotected REO significantly (P < 0.05) reduced heterophil: lymphocyte (H: L) ratio compared to all other groups. Birds receiving nanoprotected REO at 200 mg/kg diet had significantly (P ˂ 0.05) raised serum levels of immunoglobulin G (IgG) and immunoglobulin M (IgM) compared to control and other birds. Anti-SRBC titre and cell-mediated immunity improved significantly (P < 0.05) in nanoprotected REO groups. Supplementation of nanoprotected REO resulted in significantly (P < 0.05) higher values for superoxide dismutase (SOD), glutathione (GSH) and total antioxidant status (TAS). The caecal microbiota was improved in broiler birds fed diets supplemented with nanoprotected REO. The 200 mg nanoprotected REO/kg diet supplementation resulted in significantly (P < 0.05) better villus height (VH) and villus height: crypt depth (VH: CD) ratio in all the segments of the small intestine. In conclusion, feeding REO in nanoprotected form in a 200 mg/kg diet could be used as an antibiotic substitute to improve broiler chicken's lipid profile, immune-antioxidant status, and intestinal health.