Microalgae are a source of diverse high-value compounds, such as carotenoids and fatty acids, which have a potential application in aquafeeds. Some microalgae species present complex cell wall structures, which make them poorly digestible, thus limiting their use as a feed ingredient. Consequently, applying extracted compounds to aquafeeds instead of using the whole algal biomass is advantageous as this is expected to increase the bioavailability of these nutrients. The aim of this study was to evaluate the effect of the dietary inclusion (2%) of two extracts obtained from the microalga Nannochloropsis gaditana (one composed of saponifiable lipids and the other of non-saponifiable lipids), alone or in combination, on growth, muscle composition, skin color and lipid oxidation in juvenile gilthead seabream, Sparus aurata, following a 39-day trial. Overall, the inclusion of 2% of the saponifiable lipid extract did not affect the growth performance but fish muscle presented a lower percentage of docosahexaenoic acid (DHA) and a higher eicosapentaenoic acid (EPA) than that of the fish fed the diets lacking this lipidic fraction. Despite no effect being observed in fish growth performance, the inclusion of 2% of the non-saponifiable lipid extract enhanced the carotenoid content of the fish muscle, which prevented lipid oxidation, and modulated the skin pigmentation towards a yellow-greenish color. The present study confirms the success of applying both high-value microalgae lipidic extracts, alone or in combination, as feed additives for practical diets in juvenile gilthead seabream.

微藻是多种高价值化合物的来源，例如类胡萝卜素和脂肪酸，在水产饲料中具有潜在的应用。一些微藻物种具有复杂的细胞壁结构，这使其难以消化，因此限制了其作为饲料原料的用途。因此，将提取的化合物应用于水产饲料而不是使用整个藻类生物质是有利的，因为这有望增加这些养分的生物利用度。这项研究的目的是评估从微藻Nannochloropsis gaditana提取的两种提取物（一种由皂化脂质组成，另一种由非皂化脂质组成）的膳食提取物（2％）对生长的影响，金头鲷的肌肉组成，皮肤颜色和脂质氧化，经过39天的试用，Sparus aurata。总体而言，加入2％的皂化脂质提取物不会影响生长性能，但与饲喂缺乏这种脂质的饮食的鱼相比，鱼肌肉的二十二碳六烯酸（DHA）比例较低，二十碳五烯酸（EPA）比例较高分数。尽管未观察到鱼类生长性能的影响，但加入2％的非皂化脂质提取物仍可增强鱼肌肉中类胡萝卜素的含量，从而防止脂质氧化，并使皮肤色素沉着变为黄绿色。本研究证实了将高价值的微藻类脂质提取物单独或组合使用作为少年feed鱼实用饲料的饲料添加剂是成功的。