ABSTRACT - The effect of environmental temperature on performance and carcass characteristics in broilers pair-fed and two levels of metabolizable energy was evaluated. One hundred and sixty Hubbard male broilers, with 21 days of age and 791±4.12 g average initial weight were allotted either under thermoneutral environment (23.3±0.58ºC) or under hot environment (32.3±0.31ºC) up to 42 days of age. A completely randomized design in a 2 x 2 factorial arrangement (level of metabolizable energy [3075 and 3300 kcal of ME/kg] and environmental temperature, [thermoneutral and hot]) with five replicates and eight birds per experimental unit was used. The broilers received the same quantity of diet in both environments. The weight gain and feed: gain of the broiler heat stressed was negatively affected by high environmental temperature. Although the absolute carcass and cuts (drumstick, tight, legs and breast) weight and breast yield of the birds decreased in hot environmental temperature, carcass yield increased. The absolute and relative weight of broiler feathers was lower in hot condition. The absolute and relative weight of abdominal fat of the broiler heat stressed was higher for the broilers in the hot environment. The high environmental temperature determined a decrease in the absolute and relative weight of heart, liver, gizzard and gut, but it did not affect lungs and proventriculus relative weights. The heat stress negatively affected the performance, decreased the breast yield and essential organ weights, and increased the abdominal fat of broilers independent of the energy level of the diet.
pair-fed; carcass; performance; broiler; organs; environmental temperature