饲料脂肪水平对杉虎斑幼鱼生长性能、体成分、血清生化指标和肝脏酶活性的影响

Effects of dietary lipid levels on growth performance,body composition,biochemical indices and liver enzyme activities of juvenile Epinephelus fuscoguttatus♀×E.polyphekadion♂

【目的】为探讨饲料中不同脂肪水平对杉虎斑(褐点石斑鱼♀×清水石斑鱼♂,Epinephelus fuscoguttatus♀×E.polyphekadion♂)幼鱼生长性能、体成分和生化指标的影响。【方法】以鱼油为主要脂肪源,配制5种脂肪水平分别为5.86%(L1)、7.74%(L2)、9.72%(L3)、11.74%(L4)、13.68%(L5)的等氮饲料,并选用初始平均体质量为7.16 g左右的杉虎斑幼鱼,随机分为5组,每组3个重复,每个重复20尾鱼,开展为期56 d的投喂实验。【结果】1)当饲料脂肪水平为9.72%~11.74%时,杉虎斑幼鱼生长性能最佳,增重率和肥满度显著最高,饲料系数显著最低(P<0.05)。2)饲料脂肪水平对杉虎斑全鱼和肌肉水分含量影响不显著,全鱼和肌肉粗脂肪含量随脂肪水平的升高而逐渐升高,全鱼粗蛋白含量随脂肪水平的升高而逐渐降低。3)血清总蛋白、白蛋白、低密度脂蛋白含量均随饲料脂肪水平的升高而降低,血清葡萄糖、甘油三酯、总胆固醇、高密度脂蛋白含量以及谷丙转氨酶和谷草转氨酶活性随饲料脂肪水平的升高而升高。4)当饲料脂肪水平从5.86%上升到9.72%时,杉虎斑幼鱼肝脏超氧化物歧化酶、过氧化氢酶和溶菌酶活性均逐渐升高;当饲料脂肪水平超过9.72%时,过氧化氢酶活性逐渐降低;当饲料脂肪水平超过11.74%时,超氧化物歧化酶活性开始降低。5)分别以增重率和饲料系数为评价指标,进行二次多项式分析,得出杉虎斑幼鱼饲料中适宜的脂肪水平为9.77%和10.39%。【结论】本研究条件下,杉虎斑幼鱼饲料中脂肪的建议添加量为9.77%~10.39%。【意义】本研究结果可为杉虎斑幼鱼精准、高效配合饲料的开发提供参考依据。

[Objective]The study aimed to investigate the impact of dietary lipid levels on the growth performance,body composition,and biochemical indices of juvenile Epinephelus fuscoguttatus♀×E.polyphekadion♂hybrid(approximately 7.16 g).[Methods]An 8-week feeding trial was conducted,during which five isonitrogenous experimental diets containing 5.86%,7.74%,9.72%,11.74%,and 13.68%dietary lipid(referred to as L1,L2,L3,L4,and L5,respectively)were formulated using fish oil as the primary lipid source.[Results]1)The optimal growth performance of juvenile E.fuscoguttatus♀×E.polyphekadion♂was observed at a dietary lipid level of 9.72%−11.74%.At this level,weight gain rate(WGR)and condition factor(CF)significantly increased(P<0.05),while feed conversion ratio(FCR)decreased significantly(P<0.05).2)Dietary lipid levels did not significantly affect whole body and muscle moisture content(P>0.05).However,increasing dietary lipid levels led to a gradual increase in crude lipid content in both whole body and muscle,accompanied by a decrease in crude protein content in the whole body.3)As dietary lipid levels increased,the levels of serum total protein(TP),albumin(ALB),and low-density lipoprotein(LDL)decreased,while serum glucose(GLU),triglycerides(TG),total cholesterol(TC),high-density lipoprotein(HDL),alanine aminotransferase(ALT),and aspartate aminotransferase(AST)activities increased.4)Liver superoxide dismutase(SOD),catalase(CAT),and lysozyme(LZM)activities increased gradually with increasing dietary lipid levels up to 9.72%.However,CAT levels decreased when dietary lipid levels exceeded 9.72%,and SOD levels decreased when dietary lipid levels exceeded 11.74%.5)Second-order polynomial regression analysis of WGR and FCR indicated that the optimal dietary lipid level for juvenile E.fuscoguttatus♀×E.polyphekadion♂were 9.77%and 10.39%,respectively.[Conclusion]Under the conditions of this practical test,the recommended amount of fat in the diet of juvenile E.fuscoguttatus♀×E.polyphekadion♂was 9.77%−10.39%.[Significance]These results will be beneficial for the development of precise and efficient compound feed for juvenile E.fuscoguttatus♀×E.polyphekadion♂.