Effects of propolis and stocking density on growth performance, nutrient digestibility, and immune system of heat-stressed broilers

Two experiments were conducted to study the effects of propolis (bee glue; BG) supplementation and stocking density on growth performance, ileal nutrient digestibility, gut morphology, and immune response of broilers exposed to heat stress. In Experiment I, a total of 300 1-day-old male chicks (Ross 308) were assigned to six treatments, with five replications of 10 birds each. The birds were fed diet containing no additive (CON) or diet supplemented with different levels of BG (1, 2, 3, 4, and 5 g/kg of feed). Broilers-fed BG at 4 g/kg had higher average daily gain (ADG) (linear and quadratic, p