This study aimed to investigate the influences of alternative lipid sources rich in saturated and monounsaturated fatty acids (SFA and MUFA) supplemented with long-chain polyunsaturated fatty acids (LC-PUFA) on production performance and lipid metabolism of Rachycentron canadum (cobia) juveniles. An 8-week feeding trial was carried out using four isoproteic and isolipidic diets as follows: FO-D (fish oil, as control diet), SFA-D (rich in SFA), MIX-D (same levels of SFA and MUFA), and MUFA-D (rich in MUFA). Experimental diets were supplemented with arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (3, 5, and 10 g kg¹, respectively). The growth performance, fatty acid (FA) profile of liver and muscle, hepatocyte morphology, and gene expression related to the FA synthesis and oxidation on the liver were examined. In general, production performance was not impaired in fish-fed FO-free diets, supporting the hypothesis that alternative lipid sources could be used in cobia's aquafeed formulations when the LC-PUFA are adequately supplemented. High dietary SFA levels were disproportionally deposited the liver and muscle. Contrariwise MUFA was mainly deposited in the liver and muscle, reflecting the dietary inclusion levels. The main FA influencing this pattern were 12:0 and 18:1n-9. The expression of fatty acid synthase (fas) was up-regulated in the FO-D group compared to SFA-D and MIX-D groups. There were no differences in the relative expressions of carnitine palmitoyltransferase 1 (cpt-1α) and lipase lipoprotein (lpl). The liver morphology results indicated that fish-fed SFA-D presented a smaller lipid vacuoles area than those fed other experimental diets. This study shows that SFA with shorter carbon chains such as 12:0 can be administered in cobia aquafeeds to stimulate these molecules' catabolism, providing energy for growth, and retaining LC-PUFAs in tissues, especially in the muscle, exhibiting a healthier fillet for consumers.

这项研究旨在研究富含饱和和单不饱和脂肪酸（SFA和MUFA）的替代脂质来源，以及长链多不饱和脂肪酸（LC-PUFA）对加拿大短吻鲈（Rachycentron canadum（cobia））幼鱼的生产性能和脂质代谢的影响。使用以下四种同蛋白和异脂饮食进行了为期8周的喂养试验：FO-D（鱼油，作为对照饮食），SFA-D（富含SFA），MIX-D（相同的SFA和MUFA水平）和MUFA-D（富含MUFA）。实验饮食中补充了花生四烯酸（ARA），二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）（3、5和10 g kg ¹， 分别）。检查了肝脏的生长性能，肝脏和肌肉的脂肪酸（FA）谱，肝细胞形态以及与FA合成和氧化有关的基因表达。总的来说，在鱼类饲养的无FO日粮中，生产性能不会受到损害，这支持了以下假设：在适当补充LC-PUFA的情况下，替代脂质来源可用于军曹鱼的水产饲料配方中。高饮食中的SFA水平不成比例地沉积在肝脏和肌肉中。相反，MUFA主要沉积在肝脏和肌肉中，反映出膳食中的包涵体水平。影响此模式的主要FA为12：0和18：1n-9。脂肪酸合酶（fas的表达）。与SFA-D和MIX-D组相比，FO-D组的）上调。肉碱棕榈酰转移酶1（cpt-1α）和脂肪酶脂蛋白（lpl）的相对表达没有差异。肝脏的形态学结果表明，用鱼饲喂的SFA-D所呈现的脂质液泡面积要比喂饲其他实验饮食的那些小。这项研究表明，可以在军曹鱼饲料中施用碳链较短的SFA（例如12：0），以刺激这些分子的分解代谢，为生长提供能量，并在组织（尤其是肌肉）中保留LC-PUFA，从而显示出更健康的圆角消费者。