大豆浓缩蛋白替代鱼粉对大黄鱼幼鱼生长、体成分、血清生化指标及肝组织学的影响

为探索大豆浓缩蛋白(SPC)替代鱼粉水平对大黄鱼(Larimichthys crocea)幼鱼生长、体成分和血清生化指标以及肝组织学的影响。以初始体重为(10.50±0.04)g的大黄鱼幼鱼为研究对象,用SPC替代基础饲料(含40%鱼粉)0%(FM)、25%(R25)、50%(R50)、75%(R75)、100%(R100)的鱼粉制作成5种等氮(粗蛋白水平为45%)等脂(粗脂肪水平为10%)的实验饲料。各实验组以对照组(FM)饲料蛋氨酸、赖氨酸含量为基准,分别添加适量的晶体赖氨酸和蛋氨酸。养殖实验在浙江省象山县西沪港区进行,每个处理随机分配3个网箱(1.5 m×1.5 m×2 m),每个网箱放养60尾,养殖周期为56 d。结果表明,与对照组相比(FM),SPC替代鱼粉水平对大黄鱼幼鱼的增重率(WGR)、特定生长率(SGR)、存活率(SR)以及饲料系数(FCR)没有显著影响(P0.05);肌肉粗蛋白和全鱼粗蛋白无显著差异(P0.05),肌肉粗脂肪和全鱼粗脂肪含量随替代比例的增加有下降的趋势,均以R100组含量最低,肌肉水分含量和全鱼水分有上升的趋势;血清各项指标没有显著性差异,但血清总蛋白(TP)、白蛋白(ALB)含量有下降趋势,以R100组含量最低;血清胆固醇(CHOL)、甘油三酯(TG)的含量呈现出先升高后下降的趋势。从肝组织学观察中发现,SPC替代水平超过75%会对肝细胞产生损伤,引起肝细胞空泡化,脂肪堆积加重,肝细胞核逐渐溶解或缺失。综上所述,在本研究条件下,SPC替代饲料75%的鱼粉,不会对大黄鱼幼鱼的生长造成负面影响。

Effect of replacing fish meal with soybean protein concentrate on growth, body composition, serum biochemical indices, and liver histology of juvenile large yellow croaker (Larimichthys crocea)

A 56-d feeding experiment was conducted to investigate the effects of replacing fish meal in the diet with soy protein concentrate (SPC) on growth, body composition, serum biochemical indices, and liver histology of juvenile large yellow croaker,Larimichthys crocea(initial weight 10.50 g±0.04 g). The basal diet contained 40% fish meal, and five isonitrogenous (crude protein 45%) and isolipidic (crude lipid 10%) diets were formulated by replacing 0%, 25%, 50%,75%, and 100% of the fish meal with SPC and were designated the FM, R25, R50, R75, and R100 groups, respectively. All diets were supplemented with the appropriate amounts of crystalline ly-sine and methionine, based on lysine and methionine contents in the control group. Each diet was assigned ran-domly to triplicate groups of 60 ind/cage. All larvae were stocked into experimental cages (1.5 m×1.5 m×2 m) at Xihugang, Xiangshan County, Ningbo city, Zhejiang Province, China. As results, none of the experimental diets had a significant effect on the weight gain rate, specific growth rate, survival rate, or feed conversion ratio com-pared with those of fish fed the FM diet (P>0.05). Whole-body, muscle, and crude lipid contents decreased as the SPC replacement level was increased, and fish fed the R100 diet had the lowest contents. However, whole-body and muscle moisture contents increased as the SPC replacement level was increased. No differences in any of the serum biochemical indices were observed among the groups (P>0.05); briefly, serum total protein and albumin contents decreased, and fish fed the R100 diet had the lowest contents. Cholesterol and triglycerides tended to increase initially, and then decreased. Liver histology revealed serious damage to hepatocytes when SPC reached 75% (R75), as large cytoplasmic vacuole-like spaces were present, indicating excess fat accumulation, and nuclei had dissolved gradually or were absent in many of these cells. These results suggest that protein from SPC can substitute for up to 75% of the fish meal protein in the diet without affecting growth ofL. crocea.