THESIS-ABSTRACT Supplementation levels of exogenous alpha-amylase in broilers diets

Area of Science:

• Animal Nutrition and Feed Science
• Poultry Science
• Digestive Physiology

Background:

• Exogenous enzymes, such as alpha-amylase, are increasingly used in animal feed to enhance nutrient utilization and energy availability.
• Accurate determination of dietary energy is crucial for optimizing broiler performance and feed formulation.
• Digestibility indicators like Lipe® and chromic oxide are employed to assess energy values in feed.

Purpose of the Study:

• To evaluate the optimal supplementation levels of exogenous alpha-amylase in broiler diets.
• To compare the efficacy of Lipe® and chromic oxide as indicators for determining dietary energy.
• To assess the impact of alpha-amylase on broiler performance and energy metabolism.

Main Methods:

• A performance assay with 1,700 Cobb-500 male chicks was conducted using five treatments: positive control (PC), negative control (NC), and three alpha-amylase levels (200, 400, 600 g/t).
• A metabolism assay with 240 birds assessed apparent metabolizable energy corrected for nitrogen balance (AMEn) and ileal digestible energy (IDE) using Lipe® and chromic oxide as indicators.
• The NC diets were formulated with 50 and 90 kcal/kg energy reduction for the 1-21 and 22-42 day periods, respectively.

Main Results:

• No significant differences in weight gain were observed across treatments during any period (1-21, 22-42, 1-42 days).
• Feed intake was higher with 200 ppm enzyme supplementation (1-21 days), while feed conversion was better for the PC diet throughout the study.
• Exogenous alpha-amylase increased metabolizable energy but did not fully match the PC diet's energy levels, with Lipe® and total collection methods showing clearer effects.

Conclusions:

• Exogenous alpha-amylase effectively enhanced metabolizable energy in broiler diets, though not sufficiently to fully compensate for the imposed energy deficit.
• The positive control diet demonstrated superior performance, indicating limitations of the tested enzyme in mitigating significant energy reductions.
• Lipe® proved to be a reliable indicator for assessing ileal digestible energy and AMEn, showing better correlation with performance outcomes compared to chromic oxide in this study.