Channel Catfish Ictalurus punctatus reportedly require alpha‐linolenic acid (18:3[n‐3]) for normal growth. However, contradicting studies suggest that elevated dietary levels of this fatty acid might cause growth inhibition, and diets containing linoleic acid (18:2[n‐6]) alone or in combination with 18:0 and 18:1(n‐9) may support growth as well as fish oil (FO)‐based diets containing increased levels of long‐chain (LC) polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (20:5[n‐3]), docosahexaenoic acid (22:6[n‐3]), and arachidonic acid (20:4[n‐6]). Further complicating the understanding of essential fatty acid (EFA) requirements in Channel Catfish are conflicting reports suggesting that feeding LC‐PUFAs can either enhance or suppress growth. We evaluated growth performance and fatty acid composition of juvenile Channel Catfish that were fed seven diets containing n‐3 and n‐6 C₁₈ PUFAs and/or LC‐PUFAs in different combinations: a positive control containing menhaden FO, a negative control containing hydrogenated soybean oil, and experimental diets containing hydrogenated soybean oil amended with ethyl esters of 18:3(n‐3); 18:3(n‐3) and 18:2(n‐6); 22:6(n‐3); 22:6(n‐3) and 20:4(n‐6); or 20:5(n‐3), 22:6(n‐3), and 20:4(n‐6). After 18 weeks, we observed no differences in growth or conversion efficiency. However, fish that were fed diets supplemented with C₁₈ PUFAs and LC‐PUFAs numerically outperformed those fed the FO‐based positive control feed. Tissue fatty acid profiles generally mirrored that of the diet provided, except that saturates were underrepresented in the tissues. Channel Catfish that received the EFA‐free negative control feed or the diets supplemented with 18:3(n‐3) and 18:2(n‐6) or 20:4(n‐6) and 22:6(n‐3) developed elevated ratios of 22:5(n‐6) : 22:6(n‐3), whereas an elevated ratio of 20:3(n‐9) : 20:4(n‐6) was observed among fish that were fed the 22:6(n‐3) supplemented diet. Our findings suggest that C₁₈ PUFA and LC‐PUFA diets appear to equally satisfy the EFA requirements of this species; however, intact dietary LC‐PUFAs should be carefully balanced to avoid antagonistic effects of surplus n‐3 LC‐PUFA on n‐6 LC‐PUFA biosynthesis.

中文翻译：

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重新评估海Cat鱼中多不饱和脂肪酸的必要性

槽Cat鱼Ictalurus punctatus据报道，正常生长需要α-亚麻酸（18：3 [n-3]）。然而，相互矛盾的研究表明，饮食中这种脂肪酸的高水平饮食可能会抑制生长，因此，单独或与18：0和18：1（n-9）结合使用含亚油酸（18：2 [n-6]）的饮食可能支持生长，以及鱼油（FO）为基础的日粮中所含的长链（LC）多不饱和脂肪酸（PUFA）含量增加，例如二十碳五烯酸（20：5 [n-3]），二十二碳六烯酸（22 ：6 [n-3]）和花生四烯酸（20：4 [n-6]）。有矛盾的报道表明，喂食LC-PUFA可以增强或抑制生长，这使海Cat鱼对必需脂肪酸（EFA）要求的理解进一步复杂化。_18种PUFA和/或LC-PUFA的不同组合：含有menhaden FO的阳性对照，含有氢化大豆油的阴性对照和含有氢化大豆油的实验饮食，其中添加了18：3（n-3）的乙酯；18：3（n-3）和18：2（n-6）; 22：6（n-3）; 22：6（n-3）和20：4（n-6）; 或20：5（n-3），22：6（n-3）和20：4（n-6）。18周后，我们观察到生长或转化效率没有差异。但是，以补充了C _18的饮食喂养的鱼PUFA和LC-PUFA在数值上优于以FO为基础的阳性对照饲料。组织脂肪酸概况通常与所提供饮食的饮食习惯相似，只是组织中饱和脂肪酸的含量不足。接受无EFA阴性对照饲料或补充18：3（n-3）和18：2（n-6）或20：4（n-6）和22：6（n-3）的饲料的鱼）的鱼类比例提高了22：5（n-6）：22：6（n-3），而在鱼类中观察到比例升高了20：3（n-9）：20：4（n-6）接受22：6（n-3）补充饮食。我们的发现表明，C ₁₈ PUFA和LC-PUFA日粮似乎同样可以满足该物种的EFA要求。但是，完整饮食中的LC-PUFA应该谨慎地进行平衡，以避免过量的n-3 LC-PUFA对n-6 LC-PUFA生物合成的拮抗作用。