This experiment was conducted to assess the comparative effects of dietary antibiotics and oregano essential oil ( OEO ) addition on growth performance, antioxidant status and intestinal health of broilers. A total of 384 one-day-old broilers were randomly allocated to 4 treatments with 6 replicates of 16 broilers each. The 4 treatments were: an antibiotic-free control diet (control), control + 20 mg/kg colistin sulfate and 20 mg/kg virginiamycin (antibiotics), control + 200 mg/kg natural oregano essential oil ( NOEO ), and control + 200 mg/kg synthetic oregano essential oil ( SOEO ). The experiment lasted for 42 d. Results showed that birds fed with OEO had greater ( P < 0.05) average daily gain ( ADG ) and lower ( P < 0.05) feed conversion ratio ( FCR ) than those fed with control diet during d 1 to 21. Besides, birds fed with NOEO had the greatest ( P < 0.05) ADG in the four groups during d 22 to 42. The serum oxidative stress parameters showed that OEO improved ( P < 0.05) the activities of glutathione peroxidase ( GSH-Px ), superoxide dismutase ( SOD ) and glutathione reductase ( GR ) of birds on day 21 and the activity of total antioxidant capacity ( T-AOC ) of birds on d 42. Relative to control, NOEO increased ( P < 0.05) the activity of T-AOC in jejunum and decreased ( P < 0.05) the level of malondialdehyde ( MDA ) in serum and jejunum. Moreover, OEO supplementation increased ( P < 0.05) the concentrations of sIgA in duodenum and jejunum, Lactobacillus and total anaerobes in cecum, as well as activities of trypsin, chymotrypsin, lipase and amylase in duodenum, but restrained ( P < 0.05) the amount of Escherichia coli . The NOEO supplementation increased ( P < 0.05) total anaerobes of broilers on d 42 and the villus height to crypt depth ratio ( VH/CD ) of ileum. These results suggest that OEO improved antioxidant status and intestinal health of broilers which contributed to the growth performance improvement of broilers. Dietary OEO supplementation can be a promising alternative to antibiotic growth promoters for improving poultry production.

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