The metabolism of 250-day-old cocks was studied by means of a 2×2 experimental design of an open return flow respiratory calorimeter for poultry,combined with growth metabolism and fasting metabolism respiratory calorimeter tests.The results showed that the respiratory quotients and caloric production of cell 1 and cell 2 were 1.049,1.104,247.743 and 207.796 kcal/d,respectively,indicating that cell respiration was mainly carbohydrate and fat during feeding.The respiratory quotients and caloric production of cell 1 and cell 2 during hunger strike were 0.855,0.778,184.189 and 155.399 kcal/d,respectively,indicating that the main substrate of cell respiration during hunger strike was protein.Under light condition,the respiratory and heat production of cell 1 and cell 2 were 0.960,0.966,221.198 and 231.643 kcal/d,respectively.Under no light condition,the respiratory and heat production of cell 1 and cell 2 were 0.944,0.916,170.787 and 171.499 kcal/d,respectively.The results showed that chickens showed obvious circadian rhythm,and metabolism was higher in light condition than in dark condition.It can be seen that under different lighting conditions,the results of the two cells are similar,and under different feeding conditions,the difference between the two cells is large,but the results in chamber 1 maybe more accurate.