本试验旨在利用饲养试验、消化代谢试验和比较屠宰试验研究萨福克×阿勒泰杂交F1代母羊生长期代谢能（ME）和净能（NE）的需要量。选用45只2.5月龄（±3 d）、平均体重19 kg左右的萨福克×阿勒泰杂交F1代断奶母羊，其中15只用于消化代谢试验，另外30只用于比较屠宰试验。将用于消化代谢试验的15只羔羊单笼饲养，自由采食，当平均体重达到28 kg时，随机分为3组（每组5只），分别按自由采食、70%自由采食量和40%自由采食量3个水平饲喂，10 d预试期后，开始为期6 d的消化代谢试验。自由采食10 d后，将用于比较屠宰试验的30只羔羊随机分为5组（每组6只），任选1组屠宰，完成初期屠宰性能测定，剩余4组中，其中1组当平均体重达到28 kg时全部屠宰，用于中期屠宰性能测定，另外3组羊分别按自由采食、70%自由采食量和40%自由采食量3个水平饲喂，在体重达到35 kg时屠宰，用于末期屠宰性能测定。结果显示：1）维持净能（NE_m）和维持代谢能（ME_m）需要量分别为0.278 8和0.359 6 MJ/（kg W^0.75·d），ME用于维持和生长的利用效率分别为0.78和0.44；2）平均日增重为250和300 g/d时，生长净能（NE_g）需要量分别为3.38~4.68 MJ/d和4.04~5.62 MJ/d。由此得出，20~35 kg萨福克×阿勒泰杂交F1代母羊ME和NE需要量的析因模型分别为：ME=0.359 6 MJ/（kg W^0.75·d）+NE_g/0.44；NE=0.278 8 MJ/（kg W^0.75·d）+NE_g。

The purpose of this study was to investigate the metabolizable energy (ME) and net energy (NE) requirements of Suffolk×Altay crossbred F1 ewes during growing period by feeding test, digestion-metabolism experiment and comparative slaughter test. Forty-five Suffolk×Altay crossbred F1 weaned lambs, at the age of 2.5 months (±3 d) with an average body weight about 19 kg were selected, 15 of them were used for digestion and metabolism experiment, and another 30 lambs were used for comparative slaughter test. In digestion and metabolism experiment, the 15 lamps were fed separately with ad libitum feeding. When the average body weight reached 28 kg, they were randomly divided into three groups (each group had 5 lamps), and fed at three levels:100%, 70% and 40% ad libitum feeding intake, respectively. After a 10-day adjustment, a 6-day digestion and metabolism experiment was carried. After 10 days of ad libitum feeding, the 30 lamps were randomly divided into five groups (each group had 6 lamps) for comparative slaughter test and one group was selected to perform the initial slaughter performance determination. In the remaining four groups of lambs, one group was selected for medium-term slaughter performance determination, and they were slaughtered when their average body weight reached 28 kg. Other three groups were used for late slaughter performance determination, fed at three levels:100%, 70% and 40% ad libitum feeding intake, respectively, and they were slaughtered when their body weight reached 35 kg. The results showed as follows:1) the requirements of net energy (NE_m) and metabolizable energy for maintenance (ME_m) were 0.278 8 and 0.359 6 MJ/(kg W^0.75·d), and the utilization efficiencies of ME for maintenance and gain were 0.78 and 0.44, respectively. 2) The requirements of net energy for gain (NE_g) were 3.38 to 4.68 MJ/d and 4.04 to 5.62 MJ/d when average daily gain was 250 and 300 g/d, respectively. In conclusion, the requirements of ME and NE of 20 to 35 kg Suffolk×Altay crossbred F1 ewes can be counted by factorial models as below:ME=0.359 6 MJ/(kg W^0.75·d)+NE_g/0.44; NE=0.278 8 MJ/(kg W^0.75·d)+NE_g.