高植物蛋白饲料中不同水平低分子水解鱼蛋白对大菱鲆(Scophthalmus maximus L.)幼鱼生长及肝脏IGF-I受体表达的影响

本研究利用低分子水解鱼蛋白设计了4组等氮等能的高植物蛋白饲料,研究不同水平低分子水解鱼蛋白对大菱鲆(Scophthalmus maximus L.)幼鱼(4.16±0.01)g]生长性能、鱼体组成及肝脏中类胰岛素生长因子Ⅰ受体(Insulin-like growth factor receptor,IGF-IR)表达的影响.水解鱼蛋白分别替代总蛋白的5％(UF-5)、10％(UF-10)、20％(UF-20)的鱼粉,无添加FPH组为对照组(UF-0),用这4种饲料饲喂大菱鲆幼鱼84 d,结果显示,UF-0、UF-5和UF-10组的增重率、特定生长率无显著差异(P＞0.05),但显著高于UF-20组(P＜0.05);UF-0、UF-5组的饲料效率、蛋白质效率和蛋白质沉积率无显著差异(P＞0.05),而显著高于UF-10、UF-20组(P＜0.05);UF-0、UF-5和UF-10三组鱼体粗蛋白、粗脂肪含量无显著差异(P＞0.05),但显著高于UF-20组(P＜0.05);UF-5组必需氨基酸含量及必需氨基酸与非必需氨基酸比值显著高于其他3组(P＜0.05),其他3组间无显著差异(P＞0.05);肝脏中IGF-IR mRNA的表达随着水解鱼蛋白替代水平的增加而升高,且UF-20组与其他3组差异显著(P＜0.05).结果表明,适当添加低水平水解鱼蛋白(UF-5)可促进大菱鲆幼鱼的生长、提高饲料效率及促进肌肉必需氨基酸的积累;高水平添加低分子水解鱼蛋白(UF-20)会抑制其生长及饲料利用等;低分子水解鱼蛋白可提高大菱鲆肝脏中IGF-IR基因的表达量.

Effects of Small Molecule Weight Fish Protein Hydrolysate in High Plant Protein Diets on the Expression of Liver IGF-I Receptor and the Growth of Juvenile Turbot (Scophthalmus maximus L.

This experiment was conducted to investigate the effects of small molecule weight fish protein hydrolysate on the growth performance and the expression of insulin-like growth factor I receptor (IGF-IR) mRNA in the liver of juvenile turbot (Scophthalmus maximus L.). Four isonitrogenous and isoenergetic diets were formulated and fed to fish with initial weight of (4.16±0.01) g. In the experimental diets, fish meal was replaced with fish protein hydrolysate by 0% (UF-0), 5% (UF-5), 10% (UF-10), and 20% (UF-20) of total dietary protein, respectively. The experiment lasted 12 weeks. The results showed that there were no significant differences in the weight gain rate and specific growth rate among groups UF-0, UF-5 and UF-10 (P>0.05), but these groups showed higher values than group UF-20 (P<0.05). UF-0 and UF-5 showed similar feeding rate (P>0.05), which was significantly lower than that of UF-10 and UF-20 (P<0.05). The feed efficiency, protein efficiency, and protein retention effiency of UF-0 and UF-5 were significantly higher than those of UF-10 and UF-20 (P<0.05), and the parameter values of UF-10 were significantly higher than those of UF-20 (P<0.05). There were no differences in the contents of crude protein and crude lipid among groups UF-0, UF-5 and UF-10 (P>0.05), but the values in these groups were higher than those of UF-20 (P<0.05). The content of essential amino acids in the muscle and the ratio of essential amino acids to non-essential amino acids in group UF-5 was higher than those of other groups (P<0.05). It was also found that the expression of insulin-like growth factor I receptor (IGF-IR) mRNA in the liver increased with increasing levels of dietary fish protein hydrolysate, and it was higher in UF-20 compared to other three groups (P<0.05). These results indicated that low level of small molecule weight fish protein hydrolysate could improve the growth and feed utilization of juvenile turbot. However, higher level may restrain the growth. Furthermore, dietary fish protein hydrolysate could improve the expression of IGF-IR mRNA in the liver of juvenile turbot.