Abstract: In order to study the regulation of recombinant leptin on endocrine metabolism of swine, recombinant leptin were used in this feeding experiment. The results showed that endocrines metabolism of swine were regulated by injected recombinant leptin. Injecting recombinant leptin with 0.5 and 1.0 mg/kg body weight could regulate endocrines, content of serum insulin was remarkably reduced by 12% to 20% from the first to third week (P<0.05). Content of serum triiodothyronine(T3) were increased significantly from the first to the second week and the forth to sixth week (P<0.05). Tetraiodothyronine (T4) were increased significantly from the first to the third week (P<0.05). Growth hormone(GH) were all higher than control group after injected with recombinant leptin, increased by 9% to 25% from the first to forth week remarkably (P<0.05). Content of serum insulin-like growth factor-Ⅰ(IGF-Ⅰ) was higher than control group from the first to the third week and was significantly increased by 9% to 16% (P<0.05). Compared with control group, intraperitoneally injected with 0.5 and 1.0 mg/kg body weight recombinant leptin, the percentage of lean meat was increased 6.70% and 7.30% (P<0.05), the percentage of fat was decreased 16.00% and 18.75% (P<0.05), backfat thickness was decreased 18.14% and 23.01% (P<0.05)and the leaf fat depot decreased 22.95% and 24.59% (P<0.05). Carcass characteristics of swine were not significantly difference by intraperitoneally injected recombinant leptin with 0.1 mg/kg body weight(P>0.05).

Key words: leptin; endocrine metabolis; carcass characteristics; porcine