Effect of dietaryFoeniculum vulgareMill. extract on growth performance, blood metabolites, immunity and ileal microflora in male broilers

This study investigates the effect of different level of fennel extract addition to broiler chickens Ross 308 diet on growth performance, carcass quality and health status. To do this, an experiment was performed using 300 male Ross 308 broiler chicks at a thermo-neutral ambient temperature using 5 levels of fennel extract (0, 100, 200, 300 and 400 ppm). All through the growth period, the fennel extract level showed a significant effect on weight gain, economic index, although the influence is minimal during the starter period. However, the level of fennel extract has no significant influence on the amount of feed intake and feed conversion ratio, glucose, triglycerides, low-density lipoproteins, and alkaline phosphatase. The level of uric acid decreased (p = 0.001), while high-density of lipoproteins increased (p = 0.018) with an increase in the level of fennel extract. Increase in the level of fennel extract significantly improves Newcastle vaccination efficiency on day 35, and immunoglobulin production on day 42 to ensure better immunity against bacteria, viral infections, and new infections. Samples fed with fennel extract supplemented diet have higher resistance to infectious bronchitis virus but lower resistance to infectious bursal disease when compared with the samples fed with control diet. Furthermore, microflora parameters are not affected by the fennel extract level, although a better antibacterial activity was observed due to the use of fennel extract. In comparison, the best diet supplementation was obtained using 100 ppm of fennel extract due to the remarkable growth performance, carcass quality and health status.