The Influence of Drinking Water Containing Lemon Juice and Thyme Supplemented Diet on Performance and some Blood Parameters of Broilers under Heat Stress

This study was conducted to find out the effects of drinking water containing lemon juice and thyme supplemented diet on growth performance, serum concentration of cholesterol and triglycerides, heterophils (H), lymphocytes (L), H/L ratio and enzyme activity of glutathione peroxidase (GPX) in broilers under heat stress condition. The experiment was carried out as a 2 x 3 factorial arrangement with 2 levels of lemon juice (0 and 2 mL/L of drinking water) and 3 levels of thyme (0, 0.5 and 1 % of diet). Each dietary treatment consisted of 4 replicate pens (9 birds/pen). The birds were kept at 34 degrees C +/- 2 (9.00 to 17.00) from 25 to 42 d of age. Feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), H/L ratio and GPX activity and serum cholesterol concentration were not affected (P>.05) by individual addition of lemon juice or thyme; whereas, combination effect of the two additives improved performance and reduced H/L ratio and serum triglycerides concentration (P <= 0.05). Concurrent usage of 0.5 thyme and 2 mL/L of lemon juice increased FI and BWG by 229 and 165 g, respectively. Addition of 0.5 and 1% thyme to the diet and 2 mL/L lemon juice to drinking water reduced the serum triglycerides concentration by 9.8, 11.1 and 8.5 mg/dL, respectively (P <= 0.05). It is concluded that the concurrent administration of 0.5% of thyme to diet and 2 mL/L lemon juice to drinking water provides a potential protective management strategy in preventing heat-stress-related reduction in the performance of broiler chickens.