中文摘要：

以鱼粉、豆粕和明胶为主要蛋白源配制成蛋白质水平分别为31.5%、35.0%、38.5%、42.0%、45.5%、49.0%的试验饲料。选取初始均重（3.99±0.08）g的拟目乌贼（Sepia lycidas）540只,随机分成6组,每组3个重复,每个重复30只。结果表明：拟目乌贼的生长性能指标（增重率、特定生长率、成活率）均在饲料蛋白质水平为45.91%时达到最佳,除与蛋白质水平为49.72%时差异不显著（P〉0.05）外,与其他各组均有显著差异（P〈0.05）。饲料系数随蛋白质水平的升高呈先降后升的趋势,在饲料蛋白质水平为45.91%时达到最低,显著低于除49.72%组外的其他各组;蛋白质效率随着饲料中蛋白质水平的升高而显著下降（P〈0.05）。饲料蛋白质水平对肥满度与肝体比影响不显著（P〉0.05）。胃蛋白酶、胰蛋白酶、肠道脂肪酶和肝脏超氧化物歧化酶活性,随饲料蛋白质水平的增加呈先升后降的趋势,均在饲料蛋白质水平为45.91%时达到最高,胃蛋白酶和胰蛋白酶活性除与蛋白质水平为42.22%时差异不显著（P〉0.05）外,与其他各组均有显著差异（P〈0.05）;脂肪酶和肝脏超氧化物歧化酶活性与其他各组均有显著差异（P〈0.05）,而肠道淀粉酶活性则相反。肝脏谷丙转氨酶和谷草转氨酶活性随饲料蛋白质水平的增加呈先升后稳定的趋势,均在饲料蛋白质水平为49.72%时达到最大,显著高于除45.91%组外的其他各组（P〈0.05）;而饲料蛋白质水平对碱性磷酸酶活性影响不显著（P〉0.05）。乌贼肌肉粗蛋白质在饲料蛋白质水平45.91%时含量最高,显著高于除49.72%组外的其他各组（P〈0.05）;粗脂肪含量最低,显著低于其他各组（P〈0.05）;而肌肉水分和粗灰分含量不受饲料蛋白质水平的影响（P〉0.05）。拟目乌贼生长前期（4~10 g）配合饲料适宜的蛋白质水平为45.91%。

英文摘要：

In this study, we determined the effects of the dietary protein level on the growth rate, muscle composi- tion, and activities of digestive and liver enzymes of Sepia lycidas during the early growth period of the lifecycle. Six experimental diets were formulated, including fishmeal, soybean mean, and gelatine as protein sources, at various protein levels （31.5%, 35.0%, 38.5%, 42.0%, 45.5%, and 49.0%）. Totally 540 Sepia lycidas with an average body weight of 3.99 ± 0.08 g were randomly assigned into these six dietary groups; this produced groups containing thirty fish with three replicates, providing a total of ninety fish per group. It was found that at the 45.91% protein level, Sepia lycidas achieved the optimum growth rate. At this protein level, the weight gain rate, special gain rate, and survival rate showed significant difference from all other protein groups （P〈0.05）, with the exception of the 49.72% group （/9〉0.05）. Along with the increase of the dietary protein level, the feed conversion ratio initially decreased and then increased, with the lowest value found at the 45.91% protein level, which is significantly lower than those of the other groups （P〈0.05）, with the exception of the 49.72% group （P〉0.05）. The protein efficiency ratio significantly decreased as the dietary protein level increased （P〈0.05）. The condition factor and hepatosomatic index in muscles were not affected by the dietary protein level （P〉0.05）. As the protein level was increased up to 45.91%, the activities of protease, trypsin, lipase, and hepatic superoxide dismutase （SOD） increased and were significantly higher than those of other groups （P〈0.05）. Lipase and SOD continued to increase and showed the maximum activity at the 49.72% （P〉0.05） protein level. Meanwhile, the intestinal amylase activity showed the opposite trend. Levels of hepatic glutamate pyruvate transaminase and glutamic oxaloacetic transaminase initially increased before reaching a plateau, with the highest val