饲料脂肪水平对鳡幼鱼生长、体成分及血清生化指标的影响

将初始均质量(8.26±0.81)g的鳡(Elopichthys bambusa)300尾,随机分为5组,分别投喂5种脂肪水平(A组:3%、B组:6%、C组:9%、D组:12%、E组:15%)的等氮(45.64%±0.20%)、等能(16.82±0.11MJ/kg)饲料56d,研究饲料脂肪水平对鳡幼鱼生长、体成分及血清生化指标的影响。结果表明:随着饲料脂肪水平的升高,增重率、特定生长率(SGR)先升后降,B组显著高于A、E组(P<0.05),回归分析得出,饲料脂肪含量为7.71%时SGR最高;随着饲料脂肪水平的增加,饵料系数先降后升,B组显著低于A、D、E组(P<0.05),蛋白质效率先升后降,B组最高;肝体比(HSI)随饲料脂肪含量增加而升高,A组显著低于C、D、E组(P<0.05);鱼体脂肪、肝脏脂肪含量的变化趋势同HSI,体蛋白含量先升后降;随饲料脂肪水平上升,血清谷丙转氨酶、谷草转氨酶、碱性磷酸酶活力及总胆汁酸含量呈上升趋势,总蛋白、总胆固醇、甘油三酯、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇含量呈降低趋势。经分析认为,鳡最适饲料脂肪含量为7.71%,含量过高使鳡生长缓慢,脂肪代谢异常。

Effect of dietary lipid levels on growth,body composition and blood biochemical indices of juvenile yellowcheek carp (Elopichthys bambusa)

Five iso-nitrogenous(45.64%±0.20% crude protein) and iso-energetic diets(16.82±0.11 MJ/kg gross energy) with graded levels of lipid at 3%(A),6%(B),9%(C),12%(D),15%(E) were formulated to feed the fish to evaluate the effect of dietary lipid levels on growth,body composition and blood biochemical indices of juvenile yellowcheek carp(Elopichthys bambusa).Three hundred fingerlings(average weight 8.26±0.81 g) were randomly distributed in five treatments in triplicate groups with 20 fish per replicate and fed with test diets twice daily for 56 d.With the increase of dietary lipid levels,weight gain rate(WGR) and specific growth rate(SGR) increased firstly,then decreased,and were significantly higher in treatment B than that in treatments A and E(P<0.05).Protein efficiency ratio(PER),with the highest level in treatment B,increased with increasing levels of dietary lipid up to 6% and showed a declining tendency thereafter.Feed conversion ratio(FCR) showed an opposite trend with PER and was remarkably lower in treatment B than that in treatments A,D and E(P<0.05).Hepatosomatic index(HSI),whole body lipid content and liver lipid content were significantly impacted(P<0.05) by dietary lipid levels,while mesenteric fat index(MFI),condition factor(CF),whole body moisture and ash contents showed no significant differences(P>0.05).HSI in treatment A was significantly lower than that in treatments C,D and E(P<0.05).The trend of whole body protein content in the experiment was similar to SGR.The levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP) and total bile acid(TBA) in serum increased with the increase of dietary lipid levels,while total protein(TP),total cholesterol(CHO),triacylglyceride(TG),high density lipoprotein cholesterin(HDL-C) and low density lipoprotein cholesterin(LDL-C) decreased with the increase of dietary lipid contents.Analysis of SGR by quadratic model regression suggested that the dietary lipid requirement for optimal growth in juvenile Elopichthys bambusa is 7.71%(wet weight).Diet with 15% lipid could cause hepatocyte injury and abnormal fat metabolism in Elopichthys bambusa,which led to a low growth rate eventually.