Effects of dietary glutamine and gamma-aminobutyric acid on performance, carcass characteristics and serum parameters in broilers under circular heat stress

Abstract This experiment was conducted on broilers to evaluate the effects of dietary glutamine (Gln, 0 and 5 g/kg) and gamma-aminobutyric acid (GABA, 0 and 100 mg/kg) on growth performance, carcass characteristics and serum parameters in broilers under circular heat stress (HS). A total of 360 21-day-old Arbor Acre male chicks were randomly assigned to five treatment groups (6 replicates of 12 birds per cage). The positive control (PC) broilers were kept in a thermoneutral chamber (average 23 °C) and fed with a basal diet. The other four groups were kept in a circular HS chamber (30–34 °C) for 9 h (from 09:00 to 18:00). The experiment lasted from 22 to 42 day posthatch. Circular HS decreased (P