Thyme oil in broiler chickens nutrition

Experimental studies during the past three decades found beneficial influence of essential oils (EO) on lipid metabolism, ability to stimulate digestion, antimicrobial, antioxidant and antiinflammatory properties. Evaluations of the metabolic fate of phenol and alkyl-phenols concluded that these compounds are rapidly absorbed from the gastrointestinal tract, mainly conjugated with sulfate and glucuronic acid and excreted in the urine. If the capacity for conjugation is overwhelmed at high doses, alternative metabolic routes may lead to the production of reactive metabolites [1]. According to [2] there is a close relationship between the antioxidant properties and the chemical composition of the EO. The high antioxidant activity of thymol is due to the presence of phenolic OH groups which served as hydrogen donors to the peroxy radicals produced during the first step in lipid oxidation, therefore broke peroxid formation. Superoxide dismutase (SOD), glutathione peroxidase (GPx) in cells are important components of many naturally occurring antioxidant defensive systems which are important in prevention against oxidative cell damage. Thyme oil in the diet works as effective scavenger of free oxygen radicals, so can positively affect the antioxidant defense mechanism. The objective of our study was to compare the effect of six different concentrations (0.01, 0.02, 0.03, 0.04, 0.05, 0.1%) of thyme (Thymus vulgaris) EO on some antioxidant parameters in blood and plasma and to find the relationship between them and thymol content as main component of thyme EO in plasma. Among investigated antioxidant parameters only SOD significantly increased when the highest thyme oil concentration was added to the feed. Thymol plasma levels were significantly higher in chickens fed the diet containing higher (0.05%; 0.1%) thyme EO addition in comparison to the lowest thyme EO supplementation. Significant correlation (rs=0.7647; p<0.001) was found between thymol levels in feed and thymol amounts in plasma what points to the efficient absorption of thymol from the digestive tract into systemic circulation. The present study shows that in chickens biological activity of plant compounds was influenced by their concentration in the blood.