饲料中亮氨酸和异亮氨酸交互作用对牙鲆消化酶及免疫相关酶活力的影响

为研究饲料中亮氨酸(Leucine,Leu)和异亮氨酸(Isoleucine,Ile)的交互作用对牙鲆Paralichthys olivaceus肠道消化酶及肝脏免疫相关酶活力的影响,以含50%全鱼蛋白牙鲆幼鱼饲料中氨基酸组成为参考,设2个Leu水平(分别占饲料干物质的2.58%和5.08%),并将其分别与3个Ile水平(分别占饲料干物质的1.44%、2.21%和4.44%)交互制成6种试验饲料(LL-LI、LL-MI、LL-HI、HL-LI、HL-MI、HLHI);以初始体质量为(2.69±0.04)g的牙鲆为研究对象,将其随机分为6个组,每个处理组设3个重复,分别投喂含不同Leu和Ile水平的上述6种试验饲料;60 d的流水养殖试验结束后,测定牙鲆肠道消化酶(蛋白酶和脂肪酶)及肝脏免疫相关酶(总抗氧化能力T-AOC、过氧化氢酶CAT、超氧化物歧化酶SOD、酸性磷酸酶ACP、碱性磷酸酶AKP)活力。结果表明:高Ile饲料组肠道消化酶活力显著高于中间水平Ile饲料组(P0.05),且饲料中高水平的Leu可降低肠道消化酶活力(LI组除外);在低Leu处理组,当Ile≥2.21%时,随着饲料中Ile含量的增加,肝脏中CAT、SOD、ACP和AKP活力显著提高(P0.05);但在高Leu处理组,当Ile≥2.21%时,CAT、SOD和AKP活力随饲料中Ile水平的升高显著降低(P0.05)。研究表明,Leu和Ile间存在交互作用,并显著影响牙鲆肠道消化酶及部分肝脏免疫相关酶活力,且在低Leu(2.58%)水平与高Ile(4.44%)水平(LL-HI饲料组)交互作用下,牙鲆肠道消化酶及肝脏免疫相关酶活力均为最高。

Interactive effect of dietary leucine and isoleucine on digestive and immune-related enzyme activities of Japanese flounder Paralichthys olivaceus

A feeding trail was conducted to investigate the interactive effect of dietary leucine ( Leu) and isoleucine ( Ile) on activities of intestine digestive enzymes and several liver immune-related enzymes of juvenile Japanese flounder Paralichthys olivaceus. Japanese flounder juveniles with initial weights of (2. 69±0. 04)g were fed six diets ( LL-LI, LL-MI, LL-HI, HL-LI, HL-MI, HL-HI) containing two levels of dietary Leu (2. 58% and 5. 08% in dry matter) combined with three levels of dietary Ile (1. 44%, 2. 21% and 4. 44% in dry matter) with triplicate tanks per treatment for 60 days, and then intestinal digestive enzymes ( protease and Lipase) and liver immune-re-lated enzymes including catalase (CAT), superoxide dismutase(SOD), acid phosphatase (ACP), and alkaline phosphatase ( AKP) activities and total antioxidant capacity ( T-AOC) were measured in the test fish. The activi-ties of intestinal digestive enzymes in high dietary Ile were shown significantly higher than middle Ile groups ( P<0. 05) and it can be decreased in high dietary Leu(except LI). In low Leu groups, the activities of liver CAT, SOD and ACP as well as AKP was significantly increased ( P<0 . 05 ) with the increasing dietary Ile at dietary Ile level ≥2. 21%. In high Leu groups, however, the activities of CAT, SOD and AKP were found to be significantly decreased ( P<0 . 05 ) with the increase in dietary Ile level at dietary Ile level ≥2 . 21%. It can be concluded that significant interactive effect of dietary Leu and Ile is found in intestine digestive enzyme activities as well as liver anti-oxidant enzyme and enzyme related to immunity activities of Japanese flounder. The higher digestive and im-mune-related enzyme activities were observed in Japanese flounder fed diet containing low Leu (2. 58%)and high Ile (4. 44%).