Effects of dietary essential oils on productive performance, blood lipid profile, enzyme activity and immunological response of broiler chickens

Abstract

The experiment was conducted in order to investigate the effect thyme, rosemary and oregano essential oils in broiler chicken nutrition on productive performance and blood lipid profile. Beside this, enzyme activity in blood and serum level of immunoglobulin was investigated. The experiment was carried out under production conditions on a total of 1120 day-old Ross 308 strain broilers which were equally distributed into 4 dietary treatments with 8 replicates each. In the control treatment (T1) chickens were fed with a commercial diet, while experimental treatments were formed by supplementing the commercial feed with thyme, rosemary and oregano essential oils mixture in form of a commercial product, Herbal PHP, as follows: 0.05% (T2) and 0.1% (T3). In treatment T4 chickens were fed with the commercial diet supplemented with antibiotics in a concentration of 0.1% for the first 21 days of fattening. At the end of the experiment (42 day of age) chickens in experimental treatment T3 had achieved the highest body weight (2096 g) with significant difference compared to treatments T1 and T2, while the lowest feed conversion ratio was recorded in treatments T2 and T4 with significant difference compared to treatment T1. Regarding the European broiler index (EBI) the treatments did not differ significantly. Also, no significant influence of experimental diets on triglycerides and total cholesterol was observed during the experimental period. On the other side, the highest recorded enzyme activities were mainly in treatment T3 with significant difference compared to treatment T1. Immune responses was evaluated by measuring serum antibody concentration, where the IgA and IgG concentrations in T2 and T3 treatments differed significantly to treatments T1 and T4. Based on the obtained results it could be concluded that addition of essential oils in broiler diets positively affects production performance and various parameters of broilers health. Further investigation might show other positive effects of these natural additives.