Effect of thymol and carvacrol feed supplementation on performance, antioxidant enzyme activities, fatty acid composition, digestive enzyme activities, and immune response in broiler chickens

Abstract

This trial was conducted to evaluate the<br><br>effects of dietary supplementation of phytogenic product<br><br>containing an equal mixture of thymol and carvacrol<br><br>at 4 levels (0, 60, 100, and 200 mg/kg of diet) on<br><br>performance, antioxidant enzyme activities, fatty acid<br><br>composition, digestive enzyme activities, and immune<br><br>response in broiler chickens. Each of the 4 diets was fed<br><br>to 5 replicates of 12 chicks each from d 0 to 42. The<br><br>inclusion of thymol + carvacrol linearly decreased (P<br><br>&lt; 0.05) feed intake, but the highest (P &lt; 0.05) BW<br><br>gain (ADG) and feed efficiency was observed in broilers<br><br>offered 200 mg/kg of phytogenic product. The phytogenic<br><br>product linearly increased (P &lt; 0.05) superoxide<br><br>dismutase and glutathione peroxidase activities and<br><br>decreased (P &lt; 0.05) malondialdehyde level in thigh<br><br>muscle at d 42 and serum and liver at d 24 and 42. Total<br><br>saturated fatty acids were depressed (P &lt; 0.05) and<br><br>total polyunsaturated fatty acid and n-6 were linearly<br><br>increased (P &lt; 0.05) in serum and thigh by the inclusion<br><br>of phytogenic product compared with the control<br><br>diet. Supplementation with thymol + carvacrol also increased<br><br>intestinal and pancreatic trypsin, lipase, and<br><br>protease activities in 24-d-old (linear, P &lt; 0.05) but not<br><br>in 42-d-old birds. Thymol + carvacrol modified (linear,<br><br>P &lt; 0.05) immune response by increasing hypersensitivity<br><br>response, total and IgG anti-sheep red blood cell<br><br>titers, and decreasing heterophil to lymphocyte ratio<br><br>compared with the control group. However, hematological<br><br>parameters and lymphoid organ weight were not<br><br>affected by thymol + carvacrol. Thus, feed supplementation<br><br>with thymol + carvacrol enhanced performance,<br><br>increased antioxidant enzyme activities, retarded lipid<br><br>oxidation, enhanced digestive enzyme activities, and<br><br>improved immune response of broilers.