n-3/n-6长链多不饱和脂肪酸对大菱鲆幼鱼脂肪沉积、脂肪吸收及代谢相关酶活性和血清生化指标的影响

为探讨饲料中不同n-3/n-6长链多不饱和脂肪酸(LC-PUFA)对大菱鲆(Scophthalmus maximus)幼鱼生长性能及饲料利用、体组成和消化酶的影响,配制了6种不同n-3/n-6 LC-PUFA比值(29.54,D1组;23.04,D2组;18.97,D3组;9.06,D4组;6.86,D5组;3.87,D6组)的实验饲料。以大菱鲆幼鱼(12.18?0.01)g]为研究对象,在循环水养殖系统中开展了为期56 d的养殖实验。结果显示,n-3/n-6 LC-PUFA对大菱鲆幼鱼的成活率(SR)无显著影响(P0.05);增重率(WGR)随着n-3/n-6 LC-PUFA的降低呈先上升后下降趋势,D6组显著低于其他各组(P0.05);脂肪沉积率随着饲料中n-3/n-6 LC-PUFA的降低呈下降趋势,且D6组达到最小值,为14.80,显著低于其他各组(P0.05)。随着饲料中的变化,胰蛋白酶的活性呈先增强后减弱的趋势,且在D4组时达到最大值;脂肪酶活性呈上升趋势。随着饲料中n-3/n-6 LC-PUFA的变化,脂肪酸合成酶活性呈先上升后下降的趋势,最高值为D4组,显著高于其他各组(P0.05);葡萄糖-6-磷酸脱氢酶的酶活呈先上升后下降的趋势,D3组为最大值,显著高于其他各组(P0.05)。随着饲料中n-3/n-6 LC-PUFA的降低,谷草转氨酶呈先上升后下降的趋势;总蛋白、白蛋白和高密度脂蛋白胆固醇均随着饲料n-3/n-6LC-PUFA的变化呈先上升后下降的趋势,均在D5组时达到最大值。研究表明,饲料中n-3/n-6LC-PUFA的比例降低会导致大菱鲆幼鱼的脂肪沉积率降低。

Effects of n-3/n-6 n-3/ n-6 LC-PUFA on fat deposition, digestion, and lipid metabolism in juvenile turbot (Scophthalmus maximus)

An 8-week feeding trial was conducted in a recirculated system to study the effect of dietary n-3/n-6 long-chain polyunsaturated fatty acid (LC-PUFA) ratios (29.54, D1; 23.04, D2; 18.97, D3; 9.06, D4; 6.86, D5; 3.87, D6) on growth performance, whole-body fatty acid composition, and serum biochemical indices in turbot (Scophthalmus maximus). Six diets were formulated to feed six groups of juvenile turbots mean initial weight (12.18±0.01) g]. Each diet was randomly fed to triplicate groups of 35 fish per tank. There were no significant differences in the survival rate (SR) of turbot (P>0.05). With decreasing dietary n-3/n-6 LC-PUFA ratios, the weight gain rate (WGR) first increased and then decreased. The WGR of the D6 group was significantly lower than that of the other groups (P<0.05). The lipid deposition rate (LR) reduced with decreasing dietary n-3/n-6 fatty acid ratios, and the D6 group achieved 14.80, which was significant lower than that of the other group (P<0.05). The trypsin content increased as the dietary n-3/n-6 LC-PUFA level decreased from 29.54 to 9.06, and then decreased. Lipase increased with decreasing n-3/n-6 LC-PUFA. As the dietary n-3/n-6LC-PUFA level decreased, fatty acid synthetase and glucose-6-phosphate dehydrogenase first increased and then decreased. When the dietary n-3/n-6 LC- PUFA level was 9.06, fatty acid synthetase levels were significantly higher than those in the other groups (P<0.05). Additionally, glucose-6-phosphate dehydrogenase levels were significantly higher than those in the other groups (P<0.05) when the dietary n-3/n-6 LC-PUFA level was 18.97. Aspartate aminotransferase, total protein, albumin, and high-density lipoprotein cholesterol first increased and then decreased with increasing dietary n-3/n-6 LC-PUFA ratios. These results indicate that, with decreasing dietary n-3/n-6 LC-PUFA ratios, resulting in reduced lipid deposition rate of juvenile turbot.