Data from: Extrusion processing improves rainbow trout digestibility of microalgal <i>Nannochloropsis oculata</i> co-product biomass for more sustainable aquaculture diets

Aquaculture feeds include fishmeal (FM) and fish oil (FO), derived from wild-caught marine fish such as anchovy and sardines, and pose ecological, food security, and economic drawbacks for sustainable aquaculture, the world's fastest-growing agricultural sector. Protein-rich microalgal co-product is a promising alternative to unsustainably sourced fishmeal in aquaculture diets. Microalgal co-product is a defatted biomass left over after extracting omega-3-rich oil for human nutraceuticals and crude oil for fuels. In this study, we report the first evaluations of nutritive values and digestibility of raw, extrusion- and enzymatic-processed co-product of the marine microalga <i>Nannochloropsis</i><i> </i><i>oculata</i> (<i>N. oculata</i> co-product). Results allowed us to evaluate the feasibility of using processed biomass in aquafeed for rainbow trout (<i>Oncorhynchus mykiss</i>), an important model for all salmonid aquaculture. Extrusion processing temperature (90 °C vs 127 °C) influenced the nutritional value of <i>N. oculata</i>. Protein and energy levels were significantly higher in co-product from both extrusion temperature treatments than in non-extruded raw co-product. Essential amino acid levels did not differ between extrusion temperatures, except that methionine was significantly lower in coproduct from 127 °C extrusion processing than from 90 °C extrusion processing. The protein level in extrusion processed co-product was not significantly influenced by pre-cooking. We detected the highest digestibility of crude protein, energy, most of the amino acids, and omega 3 polyunsaturated fatty acids (n3 PUFA) in extruded (90 °C) <i>N. oculata</i> co-product ingredient. Nutrient digestibility of enzymatic processed <i>N. oculata</i> co-product were mostly the same as extrusion processing or lower for certain nutrients. Overall, extrusion processing of <i>N. oculata</i> at 90 °C provided the best outcome for digestible protein, and yielded an excellent source of digestible protein, amino acids, and long chain omega-3 profile for rainbow trout and which could be an alternative to replace fishmeal in rainbow trout diets.水产饲料包含鱼粉（FM）与鱼油（FO），二者均源自鳀鱼、沙丁鱼等野生捕捞海鱼。作为全球增长最快的农业领域，可持续水产养殖正面临这类原料带来的生态、粮食安全与经济层面的弊端。富含蛋白质的微藻副产物是替代来源不可持续的鱼粉的极具前景的水产养殖日粮原料，该副产物是为提取用于人类营养保健品的富含Omega-3的油脂、以及提取用于燃料的粗油后剩余的脱脂生物质。本研究首次对眼虫微拟球藻（Nannochloropsis oculata）副产物的未加工、挤压加工与酶解加工样品的营养价值与消化率进行了评估，试验结果可用于评估加工后生物质应用于虹鳟（Oncorhynchus mykiss）水产饲料的可行性，而虹鳟是所有鲑科水产养殖的重要模式物种。挤压加工温度（90℃与127℃）会影响眼虫微拟球藻副产物的营养价值，两种挤压温度处理后的副产物的蛋白质与能量水平均显著高于未挤压的原始副产物。两种温度处理间的必需氨基酸水平无显著差异，仅127℃挤压加工副产物的蛋氨酸水平显著低于90℃挤压加工组。挤压加工副产物的蛋白质水平不受预蒸煮处理的显著影响。在90℃挤压加工的眼虫微拟球藻副产物中，粗蛋白质、能量、多数氨基酸以及Omega-3多不饱和脂肪酸（n3 PUFA）的消化率最高。酶解加工的眼虫微拟球藻副产物的养分消化率大多与挤压加工组相当，部分养分的消化率则更低。总体而言，90℃下对眼虫微拟球藻进行挤压加工可获得最优的可消化蛋白质产出，可为虹鳟提供优质的可消化蛋白质、氨基酸与长链Omega-3组成原料，有望替代虹鳟日粮中的鱼粉。