Growth Performance, Carcass Characteristics, Antibody Titer and Blood Parameters in Broiler Chickens Fed Dietary Myrtle (Myrtus communis) Essential Oil as an Alternative to Antibiotic Growth Promoter

This experiment was conducted to determine the effects of Myrtle Essential Oil (MEO) on growth performance, carcass characteristics, antibody titer and blood parameters of broiler chickens. A total of 200 Ross 308 broiler chickens were allocated to five dietary treatments with four replicates of 10 birds each. Dietary treatments were prepared by formulating a corn-soybean meal-based diet free of antibiotics (Control) and supplementing the basal diet with three levels of MEO at 100, 200, 300 mg/Kg or antibiotic Flavophospholipol (FPL) at 600 mg/Kg. The results showed that diets supplemented with MEO and FPL increased the feed intake, body weight gain and improved the feed conversion ratio compared to the control treatment (P < 0.05). The relative carcass weight was significantly increased, whereas the weight of gastrointestinal tract and liver were decreased in broilers fed MEO (P < 0.05). Supplementing the basal diet with MEO increased the antibody titers against Avian Influenza Virus (AIV) and Newcastle disease Virus (NDV), although supplementing diet with 200 mg/Kg of MEO was more effective (P < 0.05). Broilers fed MEO diets especially at the level of 300 mg/Kg had a lower white blood cells count and heterophil, heterophil to lymphocyte ratio, mean corpuscular volume and mean corpuscular hemoglobin, but a higher lymphocyte and red blood cells count (P < 0.05). In conclusion, data showed that diet supplemented with MEO improved the growth performance and increased antibody titers against AIV and NDV, especially at the level of 200 mg/Kg, in broiler chickens and could be an adequate alternative to antibiotics.