Figure 4.

Effect of different environmental conditions and feed regimen on pectoralis major expression of protein metabolism related transcription factors in broilers. Relative abundances of IGF1(A), PI3Kα (B), ERK1 (C), AKT1 (D), AMPKα1 (E), mTOR (F), p70S6K (G), MyoG (H), MuRF1 (I), and MAFbx (J) mRNA was determined by real-time quantitative PCR and analyzed by the 2^-ΔΔCt method using the TN-al group as calibrator. Data were log-transformed and are presented as antilog of the geometric means with error bars representing the 95% confidence interval: $\mu \pm 1.96\times \text{sd}/\surd n$. ^a-b Different letters indicate significant difference at P < 0.05 by a Tukey's multiple comparison test. TN-al, birds reared under continuous 24°C and ad libitum feeding; aHS, birds reared under acute heat stress for 4 h on d 41; cyHS_cool, birds reared under cyclic high temperature (12 h at 35˚C and 12 h at 24˚C), ad libitum feeding, and sampled at the end of the cool phase of the night; cyHS_hot, same as cyHS_cool, but sampled after 4 h at 35°C; coHS, birds reared under continuous 35°C and ad libitum feeding; TN-coPF, birds reared under continuous 24°C and pair-fed to the coHS treatment.