不同脂肪水平下添加龙须菜对翘嘴红鲌生长、消化和脂肪代谢的影响

Effects of Gracilaria lemaneiformis on growth,digestion and lipid metabolism of juvenile Erythroculter ilishaeformis at different lipid levels

为研究不同脂肪水平下添加龙须菜对翘嘴红鲌生长、消化和脂肪代谢的影响,本试验在6%、9%和12%3个脂肪水平下,分别添加0%、5%的龙须菜藻粉(Gracilaria lemaneiformis),配制成6种等氮饲料,饲喂初始平均体质量为(11.51±0.13)g的翘嘴红鲌(Erythroculter ilishaeformis)幼鱼8周。结果表明:饲料中未添加龙须菜时,12%脂肪组翘嘴红鲌全鱼粗脂肪、肝脏脂肪、肝体比(HSI)和脏体比(VSI)比6%脂肪组分别显著升高10.34%、9.24%、11.25%、12.91%(P<0.05),但增重率比9%脂肪组显著下降11.7%(P<0.05);12%脂肪组血清总胆固醇(TC)含量比9%脂肪组显著降低24.11%(P<0.05),而血清谷草转氨酶(AST)和谷丙转氨酶(ALT)活性却显著高于6%和9%脂肪组(P<0.05)。当饲料脂肪含量为6%时,添加龙须菜组翘嘴红鲌前肠碱性磷酸酶(ALP)活性、血清甘油三酯(TG)和TC含量比未添加龙须菜组分别显著下降21.06%、17.18%、15.83%(P<0.05)。不论是否添加龙须菜,9%和12%组翘嘴红鲌前肠脂肪酶活性均显著高于6%组(P<0.05)。本研究表明,饲料脂肪含量超过适宜水平会导致翘嘴红鲌脂代谢失衡,生长性能下降。饲料中添加5%龙须菜有助于降低翘嘴红鲌全鱼和肝脏粗脂肪含量,降低血清胆固醇和甘油三酯;当饲料脂肪含量超过翘嘴红鲌适宜需求量时,龙须菜饲料可一定程度的保护肝脏。

The diets with different lipid levels(6%,9%and 12%)supplemented with 0%or 5%Gracilaria lemaneiformis(GL)respectively were fed with the juvenile Erythroculter ilishaeformis[(11.51±0.13)g]for 8 weeks to investigate the effects of GL on growth performance,digestion and lipid metabolism of the Erythroculter ilishaeformis.The results showed that when the diets did not include the GL,the crude lipid content of the whole fish and liver,the hepatosomatic index(HSI)and viscerosomatic index(VSI)of 12%lipid dietary treatment were significantly higher than that of 6%lipid dietary treatment by 10.34%,9.24%,11.25%,12.91%(P<0.05)respectively,while the weight gain(WG)was significantly lower than that of 9%lipid dietary treatment by 11.7%(P<0.05);The content of serum total cholesterol(TC)of 12%lipid dietary treatment was significantly lower than those of 9%lipid dietary treatment by 24.11%(P<0.05),while the activities of serum aspartate transaminase(AST)and alanine amiotransferase(ALT)were significantly higher than that of 6%lipid dietary treatment and 9%lipid dietary treatment(P<0.05).When dietary lipid level was at 6%level,the Alkaline phosphatase(ALP)activities of the serum and anterior intestine,the triglyceride(TG)and TC content of the serum of the fish fed with diets with the GL were significantly lower than the fish fed with diets without GL by 21.04%,17.18%,15.83%respectively(P<0.05).Whether the diets with or without GL,the lipase activities of anterior intestine of 9%and 12%lipid dietary treatment were significantly higher than that of 6%lipid dietary treatment(P<0.05).The results indicated that the growth performance of Erythroculter ilishaeformis would be decreased induced by the lipid metabolism imbalance when the dietary lipid content exceeded the appropriate level.5%GL diet was useful to reduce the crude lipid contents of whole fish and liver,and the serum TC and TG;when the dietary lipid level exceeded the suitable requirement of Erythroculter ilishaeformis,GL diet would protect the liver of the fish to some extent.