Effects of plant-derived isoquinoline alkaloids on growth performance and intestinal function of broiler chickens under heat stress

Abstract Broiler chickens reared under heat stress (HS) conditions have decreased growth performance and show metabolic and immunological alterations. This study aimed to evaluate the effect of supplementation with a standardized blend of plant-derived isoquinoline alkaloids (IQ) on the growth performance, protein catabolism, intestinal barrier function, and inflammatory status of HS-treated chickens. Three hundred and sixty 0-day-old Ross 308 male broiler chickens were randomly distributed into two treatment groups: control diet (no additives) or diet supplemented with 100 ppm IQ. At d 14, the chicks in each diet group were further divided into two groups, each of which was reared under thermoneutral (TN; 22.4 °C) or constant HS (33.0 °C) conditions until day 42. Each group consisted of six replicates with 15 birds per replicate, and chickens were provided ad libitum access to water and feed. During days 15–21, the body weight gain (BWG) and feed intake (FI) were significantly lower in the HS treatment group than in the TN group, and feed conversion ratio (FCR) was higher (P