Feed efficiency (FE) is the amount of body weight gain for a given feed intake. Improving FE through selective breeding is key for sustainable finfish aquaculture but its evaluation at individual level is technically challenging. We therefore investigated whether individual routine metabolic rate (RMR) was a predictor of individual FE in the European sea bass Dicentrarchus labrax, a major species in European mariculture. The European sea bass has three genetically distinct populations across its geographical range, namely Atlantic (AT), West Mediterranean (WM), and East Mediterranean (EM). We compared FE and RMR of fish from these three populations at 18 or 24 °C. We held 200 fish (62 AT, 66 WM, and 72 EM) in individual aquaria and fed them from ad libitum down to fasting. FI was assessed for an ad libitum feeding rate and for a fixed restricted ration (1% of metabolic body weight·day−1, with metabolic body weight = body weight0.8). After being refed 12 wk in a common tank, individual RMR was measured over 36 h by intermittent flow respirometry. There was a significant effect of temperature whereby fish at 18 °C had greater mean FE (P < 0.05) and lower RMR (P < 0.001). There was also a significant effect of population, where AT fish had lower FE (P < 0.05) and greater RMR (P < 0.001) than WM and EM, at both temperatures. Despite these differences in temperature and population means, individual FE and RMR were not significantly correlated (P > 0.05). Therefore, although the results provide evidence of an association between metabolic rate and FE, RMR was not a predictor of individual FE, for reasons that require further investigation.

中文翻译：

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欧洲鲈鱼代谢率与饲料效率之间关系的研究

饲料效率 (FE) 是指给定采食量的体重增加量。通过选择性育种提高FE是可持续有鳍鱼类水产养殖的关键，但其在个体层面的评估在技术上具有挑战性。因此，我们研究了个体常规代谢率 (RMR) 是否是欧洲鲈鱼（欧洲海水养殖的主要物种）个体 FE 的预测因子。欧洲鲈鱼在其地理范围内拥有三个遗传上不同的种群，即大西洋 (AT)、西地中海 (WM) 和东地中海 (EM)。我们比较了这三个种群的鱼在 18 或 24 °C 下的 FE 和 RMR。我们在各个水族箱中饲养了 200 条鱼（62 条 AT、66 条 WM 和 72 条 EM），并从随意喂食到禁食。FI 的评估是针对随意采食率和固定限制日粮（代谢体重的 1%·天−1，代谢体重 = 体重0.8）。在公共水箱中补充 12 周后，通过间歇式流量呼吸测定法在 36 小时内测量个体 RMR。温度有显着影响，18°C 下的鱼具有较高的平均 FE (P < 0.05) 和较低的 RMR (P < 0.001)。种群也有显着影响，在两种温度下，AT 鱼比 WM 和 EM 具有更低的 FE (P < 0.05) 和更高的 RMR (P < 0.001)。尽管温度和群体平均值存在这些差异，但个体 FE 和 RMR 并未显着相关（P > 0.05）。因此，尽管结果提供了代谢率与 FE 之间相关性的证据，但 RMR 并不是个体 FE 的预测因子，原因还需要进一步调查。