Changes in (A) HSF1, (B) HSF2, (C) HSF3, and (D) HSF4 mRNA expression levels in spleens of laying hens in the CC and FC groups before transportation (BT), immediately after transportation (0 h), and at 48 h after transportation (48 h). Lowercase letters “a, b, c” indicate significant differences (P < 0.05), and the same or nonstandard means no significant differences (P > 0.05). Abbreviations: CC, conventional cage; FC, furnished cage; HSF, heat shock factor.