Effect of cinnamon oil supplementation into broiler chicken diets on growth, carcass traits, haemato-biochemical parameters, immune function, antioxidant status and caecal microbial count

Subtherapeutic antibiotics have been used extensively as growth promoters in poultry production to enhance growth performance, treating and improving the immunity of sick and sensitive birds. However, the overuse of antibiotics has resulted in the development of antibiotic-resistant bacterium strains that may be transmitted from animals to humans (Anthony et al., 2010). The use of antibiotics as growth promoters was thus completely banned by the European Union in 2006 due to its adverse effects on human health. So, it is important to search for alternative growth promoters to avoid the negative effects and consequences of using such antibiotics. Many studies have been conducted to investigate the use of plants, plant extracts and oils as effective substitutes for antibiotics. In poultry diets, herbs and herbal products are used to replace synthetic and chemical products (Alagawany et al., 2020). Because of their antimiABSTRACT. This study aims to investigate the effect of supplementing dietary cinnamon oil (CO) into broiler chicken diets on growth performance, carcass traits, haemato-biochemical parameters, immune function, antioxidant status, and caecal microbial count. Three hundred one-day old broilers were distributed randomly, with 5 replications, into 5 groups (12 birds per replicate). Dietary treatments comprised the basal diet (control group), and the basal diet supplemented by either 10 mg/kg avilamycin or 500, 1000 and 1500 mg/kg of CO. Results indicated that birds from CO-treated groups had higher body weight, weight gain and feed conversion ratio than the control group. Also, birds from CO supplemented groups had lower total cholesterol, triglycerides, lowdensity lipoproteins than those from the control group; the lowest values were recorded in the group treated with 500 mg/kg CO. Treatment with CO increased the relative weight of spleen, thymus, bursa of Fabricius and plasma content of IgM when compared to the control and the antibiotic-treated groups. In chickens fed CO a significant decrease in caecal total microbial count, total yeast and mold count, Escherichia coli, and Salmonella was noted in comparison with the control group but was similar to animals from antibiotic-treated group. The count of lactic acid bacteria increased in the caecum of chickens fed CO in comparison with those from the control group; the lowest level was observed in the antibiotic group. So, CO can be used in broiler chicken diets as a natural alternative to antibiotic growth promoters to improve gut health and consequently growth performance. Received: 26 September 2021 Revised: 15 November 2021 Accepted: 24 February 2022