复合植物蛋白源替代鱼粉对半滑舌鳎生长、生理生化指标和肠组织结构的影响

实验以6种植物蛋白源(谷朊粉、大豆浓缩蛋白、豆粕、棉籽蛋白、花生粕和玉米蛋白粉)配比成复合植物蛋白源,以其替代半滑舌鳎(Cynoglossus semilaevis Güntuer)饲料鱼粉蛋白,共设计9种实验饲料,分别为全鱼粉组(FM)以及替代鱼粉蛋白水平分别为20%(PP20)、30%(PP30)、40%(PP40I、PP40II、PP40III和PP40IV)、60%(PP60)和80%(PP80)组,旨在最大限度替代舌鳎饲料中鱼粉蛋白,而不影响鱼体生长、生理生化指标和肠组织结构形态。以初重为(255.21±0.79)g的半滑舌鳎为研究对象,在室内流水系统中进行9周摄食生长实验,每个处理设3个重复,每桶放养15尾鱼。结果表明,各处理组实验鱼的增重率、特定生长率、饲料效率、摄食量、蛋白质效率、蛋白质沉积率和成活率均无显著性差异(P0.05);复合植物蛋白源替代鱼粉后对鱼体粗蛋白和水分含量以及血浆甘油三酯含量无显著影响(P0.05);但当复合植物蛋白源替代高比例鱼粉蛋白时,显著降低鱼体粗脂肪和血浆胆固醇含量(P0.05),且肝体比随植物蛋白源的添加而降低,PP30组显著低于FM组(P0.05);另外,4个PP40组相比,PP40III组的脏体比显著高于其他3个40%替代组。复合植物蛋白源替代鱼粉比例不超过60%时,对半滑舌鳎后肠组织结构无损伤或仅有轻微损伤,而PP80组后肠绒毛出现严重损伤现象。以上结果表明,复合植物蛋白源可以有效替代80%的鱼粉蛋白而不影响半滑舌鳎的生长性能和饲料利用率,但综合考虑鱼体生理生化和肠道组织结构指标,认为在半滑舌鳎饲料中复合植物蛋白源替代鱼粉的比例不宜超过60%。

Effects of replacing fish meal with plant-based protein on growth,physiological and biological indices,and intestinal histology in tongue sole,Cynoglossus semilaevis Güntuer

This study was conducted to replace fish meal protein (FM) with plant-based protein in the tongue sole (Cynoglossussemilaevis Günther) diet without affecting growth performance, physiological and biological indices, or intestinalhistology. Six plant ingredients (wheat gluten, soy protein concentrate, soybean meal, cottonseed meal, peanutmeal, and corn gluten meal) were selected, and eight plant-based diets were formulated to replace 20% (PP20), 30%(PP30), 40% (PP40I, PP40II, PP40III, and PP40IV), 60% (PP60), and 80% (PP80) of FM. Each diet was assigned randomlyto triplicate groups of 15 fish initial weight, (255.21 ± 0.79) g] per 500-L aquarium. The fish were maintained inflow-through aquaria and fed twice daily to apparent satiation for 9 weeks. The results showed that weight gain, specificgrowth rate, feed efficiency ratio, protein efficiency ratio, protein retention, whole-body crude protein, and plasmatriglycerides were not affected by the different plant-based protein diets compared with those of the FM-based diet (P>0.05). However, whole-body crude lipid and plasma cholesterol levels were negatively correlated with increasingplant-based protein level (P<0.05). The hepatosomatic index in fish in the PP30 treatment was significantly lower thanthat in fish in the FM treatment (P<0.05). In addition, the viscerosomatic index of the P40III diet group was significantlyhigher than that of the three other 40% FM-substituted diets. The histological results showed that intestinal villusof the hindgut were seriously damaged in the PP80 treatment, whereas they remained intact in the other treatments. Accordingto these results, 20%, 30%, 40%, 60%, and 80% FM can be replaced by plant-based protein without affectingsurvival, growth performance, or feed efficiency of C. semilaevis. However, replacing 80% of the FM with plant-basedprotein affected the physiological and histological indices, which would likely reduce growth performance and feedintake in long-term trials. Thus, our results indicate that up to 60% of FM can be replaced by plant-based protein in thetongue sole diet without affecting growth, physiological and biological indices, or intestinal histology.