Abstract A ten-week feeding trial was conducted to evaluate largemouth bass (Micropterus salmoides, LMB) responses to supplemental eicosapentaenoic acid (EPA)- and docosahexaenoic acid (DHA)-rich oils at different inclusion levels and ratios. For this purpose, eight experimental diets were formulated to contain 42% crude protein and12% lipid. Two diets were formulated to be n-3 fatty acid (FA) and EPA/DHA depleted and served as negative controls for n-3 FA or EPA + DHA, respectively. Two additional sets of three diets were designed to contain 1 or 2% EPA + DHA and three different EPA:DHA ratios (20:80, 50:50, and 80:20). Each diet was fed to triplicate groups of 15 feed-trained juvenile LMB (13.8 ± 0.2 g initial weight) stocked in 110-L glass aquaria operating as a recirculating aquaculture system. At the end of the feeding trial, the production performance of LMB fed EPA + DHA supplemented diets was unaffected by EPA + DHA levels and ratios. However, LMB fed diets with either 1 or 2% EPA + DHA displayed higher weight gain and feed efficiency compared to those fed un-supplemented diets. HSI was lower groups fed n-3 FA depleted compared to 2% EPA + DHA-fed groups. No significant differences were detected for whole-body proximate composition of LMB; while whole-body EPA and DHA concentrations were significantly affected by diet. Liver antioxidant enzyme activities were unaffected by the dietary supplementation of 1 or 2% EPA + DHA, but liver superoxide dismutase activity was significantly higher in fish fed EPA/DHA depleted diet relative fish fed the n-3 FA depleted and 1% EPA + DHA diets. On the contrary, significantly lower malondialdehyde concentration was observed in the liver of LMB fed the latter relative to fish fed the former diet. Based on the overall findings, LMB appears to be able to synthesize EPA and DHA from linolenic acid to meet physiological needs for adequate production performance and health. Nevertheless, our findings also indicate that both weight gain and feed efficiency, as well as whole-body concentrations of EPA and DHA can be enhanced in LMB by the dietary provision of around 1% EPA + DHA.

中文翻译：

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膳食二十碳五烯酸 (EPA) 和二十二碳六烯酸 (DHA) 水平和比例对大口黑鲈 (Micropterus salmoides) 生长、脂肪酸组成和肝脏抗氧化状态的影响

摘要 进行了为期十周的喂养试验，以评估大口黑鲈（Micropterus salmoides，LMB）对不同含量和比例的富含二十碳五烯酸 (EPA) 和二十二碳六烯酸 (DHA) 的油的反应。为此，配制了八种实验饮食以含有 42% 的粗蛋白和 12% 的脂质。两种饮食被配制为耗尽 n-3 脂肪酸 (FA) 和 EPA/DHA，并分别用作 n-3 FA 或 EPA + DHA 的阴性对照。另外两套三种饮食设计为包含 1% 或 2% EPA + DHA 和三种不同的 EPA:DHA 比例（20:80、50:50 和 80:20）。将每种饲料喂给三组，每组 15 只接受过饲料训练的幼鱼（13.8 ± 0.2 克初始体重），这些鱼在 110 升玻璃水族箱中作为循环水产养殖系统运行。在喂养试验结束时，LMB 饲喂 EPA + DHA 补充日粮的生产性能不受 EPA + DHA 水平和比例的影响。然而，与饲喂未补充饲料的饲料相比，饲喂 1% 或 2% EPA + DHA 的 LMB 饲料显示出更高的增重和饲料效率。与 2% EPA + DHA 喂养组相比，HSI 是低 n-3 FA 喂养组。LMB 的全身近似成分未检测到显着差异；而全身 EPA 和 DHA 浓度受饮食的显着影响。肝脏抗氧化酶活性不受日粮添加 1% 或 2% EPA + DHA 的影响，但相对于饲喂 n-3 FA 和 1% EPA + DHA 的鱼，饲喂 EPA/DHA 耗尽日粮的鱼的肝脏超氧化物歧化酶活性显着更高饮食。相反，与喂食前一种饮食的鱼相比，喂食后者的 LMB 肝脏中的丙二醛浓度显着降低。根据总体研究结果，LMB 似乎能够从亚麻酸合成 EPA 和 DHA，以满足生理需求，以实现足够的生产性能和健康。尽管如此，我们的研究结果还表明，通过提供约 1% 的 EPA + DHA，可以提高 LMB 中的体重增加和饲料效率，以及全身 EPA 和 DHA 的浓度。