Effect of embryonic thermal manipulation on the expression of growth-related genes in the broilers. (A) the mRNA expression level of growth-related genes in the hypothalamus; (B) the mRNA expression level of growth-related genes in the pituitary; (C) the mRNA expression level of growth-related genes in the liver; (D) the mRNA expression level of IGF-binding proteins in the liver. Values are mean ± SEM, n = 7. *P < 0.05, **P < 0.01, determined by an unpaired t test. PPIA served as the final reference gene. Abbreviations: CON, control group; GH, growth hormone; GHR, growth hormone receptor; GHRH, growth hormone-releasing hormone; GHRHR, growth hormone-releasing hormone receptor; IGF1/2, insulin-like growth factor1/2; IGFBP1∼5, insulin-like growth factor binding protein 1∼5; IGFR, insulin-like growth factor receptor; PPIA, Peptidylprolyl Isomerase A; SST, somatostatin; TM, thermal manipulation during embryonic development; TRH, thyrotropin-releasing hormone; TSH, thyroid-stimulating hormone; TSHβ, thyroid-stimulating hormone beta.