Developmental patterns in hormone and lipid metabolism of growing Jinhua and Landrace gilts

Miao, Z-G., Wang, L-J., Xu,, Z-R., Huang, J-F. and Wang, Y-R. 2008. Developmental patterns in hormone and lipid metabolism of growing Jinhua and Landrace gilts. Can. J. Anim. Sci. 88: 601-607. The aim of the present study was to investigate the developmental patterns of lipid metabolism, hormones and growth factor in Jinhua and Landrace gilts. Six purebred gilts of each breed were selected and slaughtered for analyses at 35, 80, and 125 d of age, respectively. Jinhua gilts contained less lean meat (P < 0.01), and more carcass fat (P < 0.05) compared with Landrace gilts. Serum leptin, insulin-like growth factor I (IGF-I) and insulin levels increased with age, whereas, free triiodothyronine (FT3) and free thyroxine (FT4) levels decreased with age in both breeds (P < 0.05). Jinhua gilts had lower (P < 0.05) serum IGF-I, FT3 and FT4 levels, and higher (P < 0.05) serum leptin and insulin levels compared with Landrace gilts. Fatty acid synthase (FAS) activity of Jinhua gilts was higher than that of Landrace gilts (P < 0.001), whereas Jinhua gilts had lower hormone-sensitive lipase (HSL) activity (P < 0.001). Jinhua gilts had lower (P < 0.05) levels of free fatty acid (FFA) and triacylglycerol (TG). These results suggest that hormone and growth factors could induce changes in lipid metabolism that inhibit fat synthesis through reducing lipogenic enzymes activities and promote fat degradation by increasing HSL activity, and therefore induce differences in carcass characteristics in the two breeds.