The lipid metabolism-related genes expression of breast and thigh muscles of ducks under FRS and NRS. (A), (C), and (E) depicted related genes expressions in breast muscle; (B), (D), and (F) depicted related genes expressions in thigh muscle. Genes of transcription factors were shown in (A) and (B), genes related to fatty acids synthesis were shown in (C) and (D), and genes related to fatty acids uptake and utilization were shown in (E) and (F). Abbreviations: FRS, floor rearing system; NRS, net rearing system; 8w, eight week; 13w, 13th week. a-c indicated a significance (P<0.05) among 8w-FRS, 8w-NRS, 13w-FRS and 13w-NRS. Genes: acetyl-CoA carboxylase, ACACA; acyl-CoA dehydrogenase long chain, ACADL; carnitine palmitoyltransferase 1A, CPT1A; fatty acid binding protein 3, FABP3, fatty acid transport protein-1, FATP1; elongation of very long chain fatty acids/fatty acid elongase-5, ELOVL5; stearoyl-CoA desaturase, SCD1; sterol regulatory element binding protein 1, SREBP1 and peroxisome proliferator-activated receptor-α, PPARα.