Different essential oils in diets of chickens: 1. Growth performance, nutrient utilisation, nitrogen excretion, carcass traits and chemical composition of meat

A study was conducted to evaluate the effect of three different types of essential oils (EOs), i.e., cinnamon oil (CNO), clove oil (CLO) and ajwain oil (AJO) as an alternative to antibiotic growth promoter (AGP) on growth performance, nutrient utilisation, nitrogen excretion, carcass characteristics, and chemical and fatty acid composition of meat of broiler chickens. Four hundred one-day-old broiler chicks were randomly divided into five dietary groups with eight replicates (n = 8) per group. Each replicate contained ten chicks. Five dietary groups consisted of: 1) a basal diet (control; without any antibiotic or EOs); 2) the basal diet + bacitracin methylene disalicylate added at a dose of 0.05 g/kg diet (AGP); 3) the basal diet + CNO at 0.3 g/kg diet (CNO); 4) the basal diet + CLO at 0.6 g/kg diet (CLO); and 5) the basal diet + AJO at 0.4 g/kg diet (AJO). At the end of the trial (39 d), one chicken from each replicate (8 chickens per group) was slaughtered for measurements of carcass traits and chemical composition of meat. Broiler chickens fed either CNO or AGP increased (P ≤ 0.05) the average daily gain, body weight and feed efficiency during the overall period. Total tract apparent retention of organic matter and crude protein increased (P ≤ 0.05) due to AGP and CNO supplementation. Nitrogen excretion per kg body weight or edible meat was reduced in AGP or CNO group compared with the control, CLO and AJO groups. Concentrations of moisture and crude protein in meat were not affected by essential oils supplementation, while ether extract content was lower in meat of the AGP group. Supplementation of CNO tended to retain the concentrations of n-3 PUFA in breast meat. From the findings of this study, it is concluded that CNO at 0.3 g/kg could be used as an alternative to AGP in commercial broiler diets to improve growth performance and nutrient utilisation while decreasing nitrogen excretion to the environment. It is further noted that the type of EOs has major influence on the growth performance of broiler chickens.