Effects of licorice (Glycyrrhiza glabra L. root) extract supplementation in drinking water on growth and selected immunological responses in broiler chickens

Objectives: This study was carried out to evaluate the effects of licorice (Glycyrrhiza glabra L. root) extract (LE) supplementation in drinking water on performance and selected immunological parameters in broiler chickens.Materials Methods: A total of 320 one-day old broiler chicks (Cobb 500) according to a completely randomized design were assigned into four treatment groups, namely 0LE, 0.1LE, 0.2LE and 0.3LE since the experimental treatments comprised a control (no inputs) and/or three levels of LE (0.1, 0.2 and 0.3 mg/L drinking water).Results Conclusion: There was no significant difference in body weight, feed intake, and feed conversion ratio among the birds given the control or the LE levels during the experiment (P 0.05). Also, LE supplementation in drinking water had no significant (P 0.05) effects on immunological parameters including antibody titers against Newcastle disease and Influenza viruses, heterophil and lymphocyte percentages and heterophil to lymphocyte (H/L) ratio as well as liver and lymphoid organ (bursa of Fabricius, thymus and spleen) weights. Based on these observations we cannot offer supplementation of LE extract for broiler chickens and further studies must be done, especially with large numbers of animals, such as those found in actual production.