Abstract
A dose-response study was conducted to investigate the metabolizable energy (ME) requirement for Lingnan chickens from 57 to 105 days of age. 1200 57-d-old slow-growing yellow-feathered male chickens were allotted to five dietary ME levels (2,805, 2,897, 2,997, 3,095 and 3,236 kcal/kg). The 2,997 kcal/kg treatment was considered to be the control level. The results revealed that the daily metabolizable energy intake increased (P < 0.01), whereas the feed intake and feed: gain ratio decreased linearly (P < 0.01) with the increment in dietary ME level. The final body weight and daily gain of the highest ME treatment tended (P > 0.05) to be greater than those obtained with the lower ME levels. The fat content in breast muscle showed a quadratic response (P < 0.05) to the increase of dietary energy level. The shear force values of breast muscle in the 2,897, 3,095 and 3,236 kcal/kg treatments were lower (P < 0.05) than that of the control. Other results were obtained regarding the body composition, meat quality, and plasma metabolites. In conclusion, the dietary ME level 3,236 kcal/kg can be recommended as the optimal ME requirement for slow-growing yellow-feathered male chickens between 57 and 105 d of age.