Evaluating the nutritional potential and microbiome effects of feedinga brewery protein isolate as an alternative to insect meal when fed to Atlantic salmon.

In this study the net protein losses associated with feeding black solider flies (BSF) with brewery waste to produce an insect meal versus producing a protein isolate from such brewery waste using isoelectric precipitation methods were modelled. Following that modelling exercise a brewery protein isolate (BPI) was prepared which had protein levels of 470 g/kg which represented an 80% yield efficiency of the protein and was higher that the BSF meal (395 g/kg). Both the BPI and BSF and a soy protein concentrate (SPC), were then fed to post-smolt Atlantic salmon (Salmo salar), to compare their nutritional qualities. In addition to the characterisation of the composition of each test ingredient, the digestibility and palatability as well as microbiome effects of each ingredient was assessed using a diet-substitution digestibility study approach. For this each of the BPI, BSF, and SPC were included in test diets at 30% inclusion with 70% of each diet coming from the same basal mash. A reference diet was prepared using the same feed preparation methods but based on 100% of the basal mash. Each diet was fed to a tank of thirty-five salmon for a one-week acclimation period before being stripped of faeces, after which the process repeated twice more to generate three replicates through time.

本研究对两种工艺的净蛋白损失情况开展建模分析：一是以啤酒废料饲喂黑水虻（Black Soldier Fly, BSF）制备昆虫蛋白粉，二是采用等电沉淀法（isoelectric precipitation）从该类啤酒废料中制备蛋白质分离物。完成上述建模研究后，研究人员制备了啤酒蛋白分离物（Brewery Protein Isolate, BPI），其蛋白含量为470 g/kg，蛋白质得率达80%，蛋白含量高于黑水虻虫粉的395 g/kg。随后将该啤酒蛋白分离物、黑水虻虫粉与大豆浓缩蛋白（Soy Protein Concentrate, SPC）投喂至大西洋鲑（Salmo salar）后稚鱼体内，以对比三者的营养品质。除对各受试原料的组成进行表征分析外，本研究还通过日粮替代消化试验法，评估了各原料的消化率、适口性以及对肠道微生物组的影响。本次试验中，啤酒蛋白分离物、黑水虻虫粉与大豆浓缩蛋白均以30%的添加比例纳入试验日粮，日粮其余70%的基质采用统一基础粉料。同时设置参照日粮，采用与试验日粮一致的饲料制备工艺，仅以100%基础粉料配制。各试验日粮均投喂至装有35尾大西洋鲑的养殖桶中，先开展为期一周的驯化适应，随后收集粪便样本；该流程重复两次，最终获得3组时间维度上的重复样本。