Effects of lipoic acid on production performance, meat quality, serum biochemistry and antioxidant function in heat-stressed broilers.

This study was aim to investigate the effects of lipoic acid (ALA) on performance, meat quality, serum biochemistry and antioxidant function of broilers under heat stress (HS). Two hundred1-day-old Cobb broilers were randomly divided into four treatment groups and each treatment consisted of 4 replicates of 10 broilers each. The treatment group adopts a 2 × 2 two-factor setting, which is divided into two diets (basic diet or 250 mg/kg ALA diet) and two temperatures (24 ± 1℃ or 33 ± 1℃). Starting from the 28th day of age, broilers are kept at room temperature (24 ± 1℃) or exposed to cyclic HS (33 ± 1℃ from 8:00 am to 18:00, 24 ± 1℃ from 18:00 to 8:00 am). HS significantly decreased serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (D-BIL), total antioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD). However, HS increased breast meat pH, serum uric acid (UA), total cholesterol (TC) and malondialdehyde (MDA). Dietary ALA significantly decreased leg meat shear force and water loss rate, serum total bilirubin(T-BIL), UA, triglyceride (TG) and MDA of broilers. However, it increased daily gain (ADG), serum D-BIL and T-SOD. There is a significant interaction between temperature and additives. HS can destroy the balance of the oxidation-antioxidant system, and lead to damage to liver and kidney function and confusion energy metabolism. Dietary ALA improves the antioxidant capacity of broilers, reduces the level of blood lipids and liver and kidney metabolism, and increases the daily gain of heat-stressed broilers.