Impact of dietary energy density on the liver health of broilers exposed to heat stress and their performance during finisher period

This study was aimed to assess the impact of dietary energy density on liver health parameters, carcass characteristics and performance of broilers exposed to heat stress. 600 Cobb male chicks were assigned to five dietary treatments and four replicates. Chicks were fed diet based on corn as main energy source and energy level based on Cobb standard (C), corn based diet with 3% lesser energy than control (T1), corn based diet with 6% lesser energy than control (T2), corn and soybean oil based diet according to Cobb standard (T3), corn and soybean oil based diet with 3% upper energy than control (T4). Temperature was increased to 34 °C for 8-hour daily from day 12 to 42 of age to induce heat stress. The highest level of ALP was for T3 and T4 and the lowest one was for T2. The highest levels of AST and ALP were for T4 and the lowest level was for T2. The lowest HSP70 gene expression was found in chicks fed T2 diet. The highest level of creatine kinase was for T4 at day 28 of age and for T3 and T4 at day 42 of age. The lowest level of creatine kinase was for T1 and T2 groups. The highest weight gain during finisher period found in T3 group andthe highest feed intake was for T2 group. The lowest feed conversion ratio was for T3 and T4 and the highest ones for C, T1 and T2 groups.Higher energy density provided with soybean oil inclusion could induce liver damages. Lower energy density in diet of broiler chickens under heat stress also resulted in liver damages and poor performance. It was concluded that soybean oil inclusion in diet of broiler chickens under heat stress caused better performance, when energy density of diet was satisfied based on strain recommendation.