Effects of different levels of dietary Tarragon (Artemisia dracunculus) on the immune system and Escherichia coli and lactobacili population of broiler chickens

The present study was performed to evaluate the effects of different levels of tarragon powder on growth performance, carcass traits, immune system and microbial population of broiler ileum using 432 Ross 308 strains in a completely randomized design. During the test, the broiler herd became infected with the flu. Experimental treatments were: diet without additives (control), and experimental diets containing 0.5, 1 or 1.5% percent of dried tarragon powder.  The performance of chickens was recorded in different stages and at the end of the experimental stages. On day 34 of the experiment, blood samples were taken from a vein to measure antibody titer against Newcastle and influenza. On day 38, two birds from each replicate were injected with diluted 0.5% SRBC solution at a rate of 2.5 cc. One week later, a blood sample was taken through a wing vein and then antibody titer levels against SRBC and serum IgM and IgG levels were determined. At the end of the experiment, 2 birds (male and female) were killed from each replication and ileal contents were collected. The weight of parts such as chest, thighs, abdominal fat, liver, heart, spleen and bursa of Fabricius was also determined. The results showed that the use of tarragon powder at all levels, without a significant effect on feed consumption, significantly improved the feed conversion ratio of birds in the final stage of rearing (p <0.05). Heart weight in birds fed diets containing tarragon powder decreased compared to the control diet (p <0.05). Diet containing 1.5% tarragon powder significantly increased serum IgM antibody production. Supplementing the diet with any of the tarragon powder levels in comparison with the control treatment significantly reduced the population of Escherichia coli in chickens and also the diet containing 0.5% of tarragon powder reduced the lactobacillus population in comparison with the control treatment. The present results indicate that the use of tarragon powder in the diet of broilers improved their growth performance. According to the findings of this study, the optimal level of tarragon powder consumption is 0.5 to 1%..