Thyme contains chemicals that might help bacterial and fungal infections, and minor irritations. It also might relieve smooth muscle spasms, such as coughing, and have antioxidant effects.
These results demonstrated that thyme oil alone showed more effective potential to improve intestinal barrier integrity and antioxidant status as well as evoking an immune response in chickens, than if diets were supplemented with both thyme oil and selenium.
In result, while thyme essential oil partially affected the performance and serum parameters, it had a marked effect on the antioxidant metabolism. For more than half a century antibiotics have been used as growth-promoting feed supplements to enhance yields in poultry production.