饲料蛋白质和脂肪水平对黑斑蛙生长、肝脏抗氧化能力及蛋脂代谢的影响

DIETARY PROTEIN AND LIPID LEVELS ON GROWTH PERFORMANCE, HEPATIC ANTIOXIDANT CAPACITY, AND PROTEIN-LIPID METABOLISM OF RANA NIGROMACULATA

  • 摘要: 本研究探讨了饲料中不同蛋白质与脂肪水平对黑斑蛙(Pelophylax nigromaculatus)生长、肝脏抗氧化能力及蛋脂代谢的影响。设计蛋白质水平(38.5%、41%、43.5%、46%)和脂肪水平(8%、10%)的4×2交互实验, 共配制8种实验饲料, 投喂初始体重为(15.00±0.10) g的黑斑蛙幼蛙8周。实验结果表明: 41P10L组黑斑蛙增重率最高, 但与38.5P10L、41P8L组间并无显著性差异(P>0.05), 且38.5P10L组蛋白质效率最高(P<0.05); 46%蛋白质组黑斑蛙平均血清总胆固醇、高密度脂蛋白胆固醇、白蛋白、尿素氮含量最高, 43.5%蛋白质组黑斑蛙平均血清甘油三酯、低密度脂蛋白胆固醇含量最高, 均显著高于38.5%蛋白组(P<0.05)。肝脏油红染色结果表明, 10%脂肪水平时黑斑蛙肝脏脂肪沉积加重, 且43.5%、46%蛋白质水平时肝脏脂肪沉积更明显(P<0.05)。46%蛋白质组血清平均谷丙转氨酶活性和谷草转氨酶活性显著高于38.5%蛋白质组(P<0.05)。肠道消化酶活性、肝脏抗氧化酶活性和丙二醛含量随着饲料蛋白质和脂肪水平的升高均呈现上升趋势。46%蛋白质组肝脏mtors6k表达量显著高于38.5%蛋白质组(P<0.05); 10%脂肪组cpt1表达量显著高于8%脂肪组(P<0.05)。综上所述, 在本实验条件下, 41%饲料蛋白质水平下虽然能够获得更高的增重率, 但会导致蛋白质效率降低, 43.5%与46%蛋白质水平则更易引起肝脏脂肪沉积加重和肝脏损伤。综合生长、蛋白质利用效率及肝脏健康等关键指标, 黑斑蛙饲料的适宜蛋白质水平为38.5%, 脂肪水平为10%。

     

    Abstract: This study was conducted to investigate the effects of different dietary protein and lipid levels on the growth performance, hepatic antioxidant capacity, and protein-lipid metabolism of juvenile Pelophylax nigromaculatus. A 4×2 factorial design was used, with dietary protein levels set at 38.5%, 41%, 43.5%, and 46%, and dietary lipid levels of 8% and 10%, resulting in the formulation of 8 experimental diets. Juvenile P. nigromaculatus with an initial body weight of (15.00±0.10) g were fed the diets for 8 weeks. The results indicated that the average weight gain rate (WGR) initially increased and then decreased with increasing dietary protein and lipid levels. The 41P10L group achieved the highest WGR, but no significant difference was observed compared with the 38.5P10L and 41P8L groups (P>0.05). Additionally, the 38.5P10L group showed the highest protein efficiency ratio (PER) (P<0.05). Among all groups, the 46% protein group had the highest average contents of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), albumin (ALB), and urea nitrogen (BUN), while the 43.5% protein group exhibited the highest average contents of serum triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C)—with these respective indices in both groups being significantly higher than those in the 38.5% protein group (P<0.05). The results of oil red O staining indicated that lipid deposition in the liver of P. nigromaculatus was aggravated at the 10% lipid level, particularly under 43.5% and 46% protein levels (P<0.05). The average serum activities of glutamic-pyruvic transaminase (GPT) and glutamic-oxaloacetic transaminase (GOT) in the 46% protein group were significantly higher than those in the 38.5% protein group (P<0.05). Additionally, the average activities of intestinal digestive enzymes, hepatic antioxidant enzymes, and the malondialdehyde (MDA) content increased with the elevation of dietary protein and lipid levels. Regarding gene expression, the relative expression levels of hepatic mtor and s6k in the 46% protein group were significantly higher than those in the 38.5% protein group (P<0.05), while the hepatic cpt1 expression level in the 10% lipid group was significantly higher than that in the 8% lipid group (P<0.05). In conclusion, although a dietary protein level of 41% supported higher WGR, it resulted in reduced PER. In contrast, dietary protein levels of 43.5% and 46% were more prone to induce aggravated hepatic lipid deposition and hepatic injury. Considering comprehensive factors including growth performance, protein utilization efficiency, and hepatic health, the optimal dietary protein level for P. nigromaculatus was determined to be 38.5%, with an optimal dietary lipid level of 10%.

     

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