Effect of different levels of rapeseed oil and garden thyme essential oil onperformance, immune traits and intestinal morphology of broiler chickens

The effect of garden thyme essential oil (TEO) and rapeseed oil (RO) on performance, immune traits and intestinal morphology using 432 one-dayoldRoss 308 male broiler as a (3x3) factorial experiment in a completely randomized design including different levels of TEO (0, 300 and 500 ppm)and RO (1, 3 and 5 percentage) were evaluated with 9 treatments and 4 replicates. Throughout the rearing period, broiler chickens receiving 3%gained more weight than 1% of RO and chickens receiving 300 ppm gained more weight than those without TEO (P˂0.05). The use of 3% RO + 300ppm TEO increased the thigh percentage compared to 1% RO. At 1 and 5 percentage levels of RO, with increasing levels of TEO in the diet, bloodcholesterol and LDL concentrations decreased and blood HDL increased (P<0.01). Levels of 3% and 5% of RO + 300 and 500 ppm of TEO in broilerchicken diets increased lymphocyte percentage and antibody titer against Newcastle disease and decreased heterophil percentage and heterophil tolymphocyte ratio of blood (P<0.05). Broiler chickens receiving diet containing TEO had the highest ratio of villi height to crypt depth (P<0.01). Basedon the results, the level of 3% rapeseed oil + 300 ppm thyme essential oil in the diet of broiler chickens can be used to improve performance,immunity and biochemical traits of blood.