Growth performance and nutrient digestibility of broilers fed low-energy corn-soybean meal-based diets supplemented with an exogenous enzyme cocktail as a combined activity

The experiment aimed to evaluate the effects of supplementing a standard broiler diet, formulated based on corn and soybean meal (CSBM), with two levels of an exogenous enzyme (EZ) cocktail (0 and 0.05%), under two dietary metabolizable energy (ME) levels - normal (positive control, PC) and low (negative control, NC). From 0 to 35 d, 288 Ross 308 chicks were distributed across four treatments with 12 replicates of six chicks each. Growth performance was evaluated during the starter, grower, finisher, and cumulative period. At 35 d, blood samples were collected to measure serum metabolite concentrations, and birds were processed to determine carcass traits. Ileum segments were prepared for histological measurements, and excreta were collected to analyze apparent nutrient digestibility. Data were analyzed employing two-way ANOVA and Tukey's test. The results indicated no significant interaction between ME and EZ for any measured parameter. The EZ supplementation improved feed conversion rate (FCR) during the starter phase, and improved feed intake, body weight gain (BWG), FCR, and production efficiency index (PEI) during the grower phase; PEI during the finisher phase; and BWG, FCR, PEI, and final BW over the cumulative phase. Furthermore, EZ enhanced dressing percentage, breast yield, villi length, retention of crude protein, and nitrogen-corrected ME (AMEn), while also increasing glucose concentration and reducing the relative weight of the gizzard and intestine. Compared with the NC diet, the PC diet enhanced feed efficiency across the grower, finisher, and cumulative phases and increased AMEn and triglyceride levels. Supplementing ME-adequate CSBM diets with an EZ cocktail can boost the nutrient digestibility and growth efficiency of broilers.