高脂饲料中胆汁酸水平对齐口裂腹鱼肠道组织结构及脂肪代谢酶活性的影响

为探索高脂饲料中添加胆汁酸对齐口裂腹鱼幼鱼肠道组织结构及几种脂肪代谢酶活性的影响,以360尾初始体质量为(12.74±0.14)g的健康齐口裂腹鱼幼鱼为实验对象,随机分为4组,每组3个重复,每个重复30尾实验鱼,分别投喂添加了0、75、150和300mg/kg胆汁酸的4种实验饲料,养殖时间为70 d。结果显示,胆汁酸浓度从0增大到75 mg/kg时,齐口裂腹鱼前肠和中肠管壁厚度及肠绒毛高度显著升高,前肠皱襞宽度显著降低。而当胆汁酸浓度再进一步增大时,实验鱼前肠和中肠管壁厚度及肠绒毛高度则升高不明显,其皱襞宽度也降低不显著。未添加胆汁酸的实验组中齐口裂腹鱼前肠和中肠纹状缘畸形或脱落现象严重,随着胆汁酸添加量的增加,逐渐减少至消失。齐口裂腹鱼肠道中脂肪酶(LPS)及肝胰脏中脂蛋白酯酶(LPL)、肝酯酶(HL)和总酯酶(TL)活性均随胆汁酸添加量的增加而呈先升高后趋于稳定的变化趋势。且LPS、LPL活性均在胆汁酸添加量为300 mg/kg时最强(分别为2881.17 U/g和14.43 U/mg prot);HL、TL活性则在胆汁酸添加量为150 mg/kg时活性最强(分别为43.70和58.03 U/mg prot)。但LPS、LPL、HL和TL活性在150与300mg/kg组均无显著差异。研究表明,在饲料中添加75~150 mg/kg的外源胆汁酸能提高齐口裂腹鱼幼鱼脂肪代谢酶的活性,促进对饲料脂肪的代谢和利用,还能改善齐口裂腹鱼幼鱼肠道结构,保护肠道健康。

Effect of bile acid level in high lipid diet on the intestinal structure and lipid metabolic enzymes activities of juvenile Schizothorax prenanti

This experiment was conducted to examine the effect of high lipid diet on the intestinal structure and lipid metabolism enzymes in juvenile Schizothorax prenanti treated with bile acid. In our study, a total of 360 juvenile S. prenanti, with average body weight of (12.74±0.14) g, were randomly distributed into four groups with three replicates each. The high lipid diet diets with different bile acid levels (0, 75, 150 and 300 mg/kg) were fed to juvenile S. prenanti for 70 days. The results showed that the foregut and midgut intestinal tube wall thickness, as well as villi length significantly increased with increasing dietary bile acid levels up to 75 mg/kg diet, and remained nearly constant thereafter. Meanwhile, the foregut plica width was significantly reduced with increasing dietary bile acid levels up to 75 mg/kg diet, where the response reached a plateau. In addition, we found that the intestinal lipase (LPS), lipoprotein lipase (LPL), hepatic lipase (HL) and total lipase (TL) increased firstly and then tended to stabilize. Interestingly, the activities of LPS and LPL of juvenile S. prenanti were the highest for fish fed with diet containing 300 mg/kg bile acid diet, which were 2881.17 U/g and 14.43 U/mg prot, respectively. While the activities of HL and TL were highest for fish fed 150 mg bile acid/kg diet, which were 43.70 and 58.03 U/mg prot, respectively. Collectively, the results indicated that 75-150 mg bile acid/kg diet can improve the fat metabolism enzyme activity, promote the utiligation of diet lipid and improve intestinal structure, and protect the intestinal health in juvenile S. prenanti.