The Use of Licorice Extract for Alleviate the Adverse Effects of Heat Stress on Physiological Performance of Broiler Chickens

This study was conducted to determine the physiological mechanisms expected to be involved in alleviate the detrimental effects of heat stress on broiler chickens by supplementing drinking water with licorice extract (LE). A total of 600 broiler chicks, one day old were used. Birds have been assigned to 4 treatment groups with 3 replicates of 50 chicks each (150 chicks per treatment). Birds in the first treatment (T1) provided drinking water alone and considered as a control group, whereas birds in treatments 2 (T2), 3 (T3) and 4 (T4) provided drinking water supplemented with 150, 300 or 450 mg LE / liter, respectively. Hematological traits included in this study were: Erythrocyte counts (RBC), hemoglobin concentration (Hb), thrombocyte counts (Thr), leukocyte counts (WBC), heterophil / lymphocyte ratio (H / L ratio), hematocrit (pcv) and plasma uric acid (Uri), glucose (Glu), cholesterol (Cho), Protein (Pro), aspartate aminotransaminase activity (AST), alkaline phosphatase activity (ALP), calcium (Cal) and phosphorus (Pho). Results revealed that inclusion of the LE in the drinking water of broiler chickens exposed to heat stress resulted in significant (p < 0.05) increase in RBC, Hb, Thr, WBC, PCV, and plasma Uri, Glu, AST, ALP, Ca and Pho and significant (p < 0.05) decrease in H / L ratio, and plasma Cho and Pro compared with T1. However, T4 recorded the best results with relation to all blood characteristics included in this experiment.It was concluded from this study that supplementation of LE particularly at the level of 450 mg / liter to the drinking water of broiler chickens exposed to heat stress can depress the adverse effects of heat stress on general physiological status of broiler chickens.