| Two experiments were conducted to evaluate the suitable dietary CP and ME concentrations for broilers during the middle (29～49d) and last (50-70d) peroids.Experiment 1:A total of 1620 52-day-old straight-run Erlang mountain chickens were randomly assigned to one of nine treatments with 3×3 completed randomized arrangement. The ME concentrations included 10.88,12.13,and 13.39 MJ/kg of diet; the CP concentrations included 14%,17%, and 20%. Each dietary treatment was replicated 6 times with 30 sex-mixed chicks each replicate. The experiment inculde 23d. According the result of performance to choose 6 groups for the metabolic test. The results show that:1.The dietary CP level had no significant(P>0.05) effect on the ABW,ADFI,F/G at 52-75d.2.The dietary ME level had no significant(P> 0.05)effect on the ABW,ADFI at 52d to 75d; the F/G at 52-75d was significantly (P <0.05) improved with the decrease of dietary ME.3.There was a significant (P<0.01) interaction between the effects of dietary energy and crude protein levels on F/G,The treatment of, ME 13.39 MJ/kg and CP 20% is lowest.4.The dietary ME level had significant (P<0.01)effect on the Net rate of half-bore and Abdominal fat rate. In conclusion, The dietary ME level have effect on performances of Erlang Mountain chickens at 52-75d, improve it to achive F/G better; the optimal dietary energy and crude protein level was ME 13.39MJ/kg and CP 20% based on the F/G and body weight gain of 52-75d; ME 13.39MJ /kg and CP 17% based on the slaughter performance of 52-75d.Experiment 2:A total of 1620 1-day-old straight-run Erlang mountain chickens were randomly assigned to one of nine treatments with 3×3 completed randomized arrangement. The ME concentrations included 10.88,12.13,and 13.39 MJ/kg of diet; the CP concentrations included 15%,18%, and 21%.Each dietary treatment was replicated 6 times with 30 sex-mixed chicks each replicate. The same diets were designed to contain ME 10.88MJ/kg and CP 20% at 0-28d and contain ME 10.88MJ/kg and CP 20% at 50-70d. At 29-49d the experimental using different of 9 diets. The experiment inculde 70d. According the result of performance to choose 6 groups for the metabolic test. The results show that:1.The dietary CP levels of middle and last stage old chicken significantly (P<0.05) decreased the F/G of 29-49d with the increase of energy level, but The dietary CP level at middle stage had no significant(P>0.05)effect on the F/G at 29d to 70d; The dietary CP level at middle stage had no significant(P>0.05)effect on the ADFI of Erlang Mountain cocks middle and the late stage,but had significant (P<0.01)effect on the ADFI of Erlang Mountain cocks at last stage; The dietary CP level at middle stage had no significant (P>0.05)effect on the ADFI,ABW and slaughter performance.2.The dietary energy levels of middle stage old chicken significantly (P<0.05) decreased the ADFI and F/G of 29-49d,50-70d and 29-70d with the increase of energy level, it no significantly (P<0.05) to ABW. The Abdominal fat rate at 49d was significantly (P< 0.05) improved with the increase of dietary CP at 29-49d,but another slaughter performance have no significantly (P<0.05).3.There was a significant (P<0.05) interaction between the effects of dietary energy and crude protein levels on F/G and ABW of Erlang Mountain hens at 29-49d, slaughter performance of 70d, to another have no significantly (P<0.05).4.the meat quality of Erlang Mountain improved with the increase of dietary ME, but decreased of dietary CP. In conclusion, the optimal dietary energy and crude protein level was ME 12.13MJ/kg and CP 18% based on the F/G and body weight gain of Erlang Mountain cocks at 29-49d; ME 13.39MJ/kg and CP 18% based on the F/G and body weight gain of Erlang Mountain hens at 29-49d; 3)ME 12.13MJ/kg and CP 18% based on the slaughter performance of 49d; During 29-70d,ME 13.39MJ/kg and CP 18% based on the F/G of Erlang Mountain hens at 29-49d. There were some compensate growth after 49d based on the ABW at 70d.
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