The objective was to evaluate diets with different levels of CP and fat, and their effect on feathering and hematological and biochemical parameters of broilers submitted to cyclic heat stress (HS) since 21 d of age or in thermoneutral environment (TN). A factorial 2 x 2 + 2 was used, with two environments-TN (21-25ºC and RH 73%) and HS (25-32ºC and RH 65%), and two diets (D) - control (2.4% fat and 19.5%CP) and summer (SD) (4.0% fat and 18.5% CP with Lys and Met + Cys supplemented at the control diet level). On TN environment, two more diets were formulates, with the amount equalized (pair feed) of ration in relation to HS, for both diet. Biochemistry and hematological analyses were carried out in six birds/treatment, at 42 days-old, and bursa and spleen weighed and feather yield (FY) was evaluated in 288 birds. The DV for broiler in EPC was capable to attenuate part of the alterations observed in the heat, resulting in better relative weight of bursa, small number of total leukocytes and smaller heterophils/lynphocytes relationship. Environment and diets did not change biochemistry serum parameters. Birds with ad libitum intake in the ATN showed FY 15% greater that birds in the HS, even so the feed restriction decreased RP for the birds with pair feed intake. Diets did not influence FY. Data suggests that either HS or feed intake restriction are additive factors that decrease feather production.
fat; feathering; heat stress; hematology; protein
