Fig. 4.

Plasma corticosterone concentration in broiler chicken plasma. Broilers of two different hybrid strains, Ross 308 (RO), Red JA Cou Nu (CN), were maintained from the 4th to the 8th week of age at two different environmental temperatures: 60 RO and 60 CN (in separate pens), at 34 °C (high temperature, HT), and other 60 RO and 60 CN (in separate pens), at 22 °C (control temperature, CT). Each histogram represents the average level (means ± s.e.m. as error bar) of 40 broilers (20 birds/strain). (*) indicate significant differences (P < 0.05) between RO (HT + CT) and CN (HT + CT), and between HT (RO + CN) and CT (RO + CN).