Effects of simultaneous modulation of dietary metabolizable energy and crude protein on growth performance, nutrient utilization and carcass traits of broilers

This study evaluated the effects of simultaneous modulation of dietary metabolizable energy (ME) and crude protein (CP) levels on Cobb 500 broilers in commercial production. A total of 900 1-day-old male Cobb 500 broilers were randomly divided into low-, medium- and high-level groups (L, M, H), with 10 replicates of 30 broilers each. The M group received the diet aligned with standard Cobb 500 nutritional specifications, whereas the L and H groups were synchronised, adjusting ME by ±0.20 MJ/kg and CP by ±0.50 percentage points, respectively. Growth performance, cumulative ME and CP intake, apparent total tract digestibility (ATTD) and carcass traits were evaluated and analyzed via one-way ANOVA using SPSS 22.0. The broilers in the H, M and L groups reached the target 3.0 kg market weight at 40 d, 42 d and 44 d, respectively. However, no significant differences were observed among the treatments in cumulative ME and CP intake, ATTD or carcass traits (p > 0.05). These findings indicate that simultaneous increases in dietary ME and CP can shorten the market age by up to 2 d in Cobb 500 broilers without adversely affecting nutrient utilization or carcass characteristics.