Effects of dietary supplementation with oregano essential oil on growth performance, carcass traits and jejunal morphology in broiler chickens

This study was conducted to investigate the effects of diets containing oregano essential oil (OEO) on growth performance, carcass traits and intestinal morphology of broilers during a 42-day production period. A total of 448 one-day-old Arbor Acres broilers were randomly distributed into 4 dietary treatments with 7 replicate pens per treatment and 16 birds per pen. The dietary treatments were as follows: (1) corn-soybean basal diet (control, CON), (2) CON + 8 mg/kg avilamycin (AVI), (3) CON + 300 mg/kg OEO preparation (OEO300), and (4) CON + 600 mg/kg OEO preparation (OEO600). The results showed that both OEO300 and OEO600 groups increased (P=0.007) the final body weight compared to the CON group. On day 21, OEO600 increased average daily gain (ADG) and lowered feed conversion ratio (both P<0.05) compared to the CON. On day 42, both OEO300 and OEO600 groups increased (P<0.05)ADG and average daily feed intake (ADFI) compared to the CON. Moreover, OEO600 increased (P<0.05) ADG and ADFI compared with AVI. Carcass parameters were similar among avilamycin and OEO preparation treatments. Avilamycin and OEO supplementation improved (P<0.05) the dressing percentage and eviscerated rate compared with CON. The broilers fed with OEO600 had the highest (P=0.003) breast muscle percentage, and the lowest (P=0.008) abdominal fat percentage. All treatments had no effect on the villus height in the jejunum of broilers. However, OEO300 and OEO600 decreased (P=0.000) the crypt depth and increased (P=0.000) the villus height to crypt depth ratio compared with CON and AVI, which may contribute to the improvement of growth performance. In conclusion, OEO supplementation exhibited a significantly positive effect on the growth performance, carcass traits and intestinal health of broilers, indicating that OEO may be a promising alternative to antibiotic growth promoters. (C) 2016 Elsevier B.V. All rights reserved.