Gamma aminobutyric acid (GABA) is one of the inhibitory neurotransmitters that may have the ability to relieve the intensity of stress. Heat stress remains a major threat for duck production in summer in most areas of China. The current study was conducted to investigate the effect of dietary GABA on performance parameters and plasma metabolites of heat exposed ducks. Two thousand Cherry Valley ducks (19 d) were randomly divided into two groups, each group with five replicates. One group was fed basal diet and the other fed basal diet with 100 mg/kg GABA for 42 days. The ambient temperature from day 19 to 42 was 29.7 ± 3.5°C. Growth performance and rectal temperature were determined on days 19, 32 and 42. Plasma samples were collected at day 42. The results showed that dietary GABA had no significant effect on ducks’ rectal temperature but decreased the feed intake (P<0.05). No differences were observed on survival rate, body weight, and dressing percentage. Gamma aminobutyric acid decreased feed conversion ratios (P<0.05) and plasma glucose concentration (P<0.05). However, GABA increased plasma concentrations of triglyceride and free fatty acids (P<0.05). No differences of GABA concentrations were found in the blood, heart, liver, and kidney between the two groups, but was increased in the brain of GABA group (P<0.05). These findings suggest that 100 mg/kg dietary GABA decreased feed intake and increased fat mobilization in ducks exposed to high ambient temperature, which might attenuate the adverse effects of heat stress on duck production.
