Abstract Releasing hatchery-reared juveniles in the wild can mitigate the general decline in the natural stocks of European lobster, Homarus gammarus, L.. However, growth and survival rates in lobster culture are low, presumably due to suboptimal nutrition and feeding. With the aim of determining appropriate nutrient levels, we tested different formulated extruded feeds for the culture of juvenile European lobster. Baseline metabolism (standard metabolic rate, SMR), in combination with the metabolic cost of feeding (specific dynamic action, SDA), and nitrogen retention during digestion and assimilation was investigated for six experimental diets. Diets were formulated to contain two different levels of protein (400 and 500 g kg−1), with three lipid to carbohydrate (L:CHO) ratios (low, medium, and high). These experimental diets were tested over a 32-day period, against a conventional control diet (Antarctic krill, Euphausia superba). During this period, the growth performance of the juveniles was assessed as molting frequency, increments in carapace length and whole body wet weight. At the end of the growth performance trial, oxygen consumption (MO2) and nitrogen excretion rates of individual lobsters were determined prior to and following the ingestion of a single meal. Molting occurred more frequently in juveniles fed with krill and krill resulted in a significantly higher specific growth rate than experimental dry feeds except for the 500-low diet. However, lobsters fed any of the three 500 and the 400-low diets had carapace length increments, SMR, SDA, and nitrogen retention similar to those fed the krill diet. Results suggest that protein is an important macronutrient for juveniles of this species and must be included above 40%. Also, lobsters have a dietary requirement for carbohydrates ranging from 24% to 35% probably related to the need for glycogen in chitin synthesis. The lower the protein content, the higher the requirement in carbohydrates.

中文翻译：

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日粮蛋白质、脂质和碳水化合物水平对欧洲龙虾幼年性能、代谢率和氮保留的影响 (Homarus gammarus, L.)

摘要 在野外释放孵化场饲养的幼体可以缓解欧洲龙虾 (Homarus gammarus, L.) 自然种群的普遍下降。然而，龙虾养殖的生长率和成活率较低，这可能是由于营养和饲养欠佳所致。为了确定适当的营养水平，我们测试了用于培养欧洲龙虾幼仔的不同配方膨化饲料。研究了六种实验饮食的基线代谢（标准代谢率，SMR），结合喂养的代谢成本（特定动态作用，SDA）以及消化和同化过程中的氮保留。饮食被配制为包含两种不同水平的蛋白质（400 和 500 g kg-1），具有三种脂质与碳水化合物 (L:CHO) 比率（低、中和高）。这些实验饮食在 32 天的时间内与常规对照饮食（南极磷虾，Euphausia superba）进行了测试。在此期间，幼鱼的生长性能通过蜕皮频率、背甲长度的增加和全身湿重进行评估。在生长性能试验结束时，在摄入单餐之前和之后确定单个龙虾的耗氧量 (MO2) 和氮排泄率。用磷虾喂养的幼鱼更频繁地蜕皮，除 500-low 饲料外，磷虾的比生长率明显高于实验干饲料。然而，喂食 3 种 500 和 400 低饮食中的任何一种的龙虾的背甲长度增加、SMR、SDA 和氮保留与喂食磷虾饮食的龙虾相似。结果表明，蛋白质是该物种幼鱼的重要常量营养素，必须包含在 40% 以上。此外，龙虾对碳水化合物的饮食需求为 24% 至 35%，这可能与几丁质合成中对糖原的需求有关。蛋白质含量越低，对碳水化合物的需求量就越高。