Effects of dietary thyme and rosemary essential oils on biochemical parameters, anti-oxidant metabolism, small intestinal morphology and myofiber structure of superficial pectoral and biceps femoris muscles in broilers

This study was aimed at determining the effects of dietary supplementation with thyme essential oil (TEO) and rosemary essential oil (REO) on blood parameters, the anti-oxidant metabolism in the liver, breast and drumstick muscle tissues, the morphology of the small intestine, and the myofibril structure of the superficial pectoral and biceps femoris muscles. For this purpose, 400 three-day-old male Ross 308 chicks were used. Five groups, each comprising 80 broilers, were established. The control group was fed on a basal diet alone and groups thyme-1, thyme-2, rosemary-1 and rosemary-2 received basal diets supplemented with 0.15 g kg-1 of TEO, 0.30 g kg-1 of TEO, 0.10 g kg-1 of REO and 0.20 g kg-1 of REO, respectively. The serum total cholesterol and low-density lipoprotein levels were decreased significantly in group thyme-1. Dietary TEO and REO significantly increased glutathione levels in all tissues. Drumstick catalase activity was significantly increased in groups thyme-1, thyme-2 and rosemary-2. Superoxide dismutase activity was significantly increased in the breast muscle of all groups that received dietary TEO and REO. Histomorphometrical analyses demonstrated that dietary supplementation with TEO and REO increased both crypt depth and villus height in the small intestine. In result, the tested doses of dietary TEO and REO were ascertained to improve the intestinal morphology and to increase the anti-oxidant metabolism mainly in the breast muscle, the drumstick muscle and liver.