饲料蛋白质水平对洛氏鱥蛋白质代谢酶及抗氧化能力的影响

Effects of Different Dietary Protein Levels on Protein Metabolizing Enzyme and Antioxidant Capacity of Rhynchocypris lagowskii Dybowski

为研究饲料蛋白质水平对洛氏鱥(Rhynchocypris lagowskii Dybowski)蛋白质代谢酶及抗氧化酶活性的影响。以洛氏鱥幼鱼[(6.98±0.01)g]为研究对象,以鱼粉、棉粕、豆粕及菜粕为蛋白源,混合油脂[V(玉米油)∶V(鱼油)=1∶1]为脂肪源,配制成5种蛋白质水平(24.98%,30. 02%,34.99%,40.01%,44.98%)等脂肪(6.0%)的配合饲料,进行了8周的饲养试验。饲养试验结束后,采用福林-酚法测定洛氏鱥肝胰脏及肠道的蛋白酶活性,用试剂盒测定肝胰脏的谷草转氨酶(AST)、谷丙转氨酶(ALT)、丙二醛(MDA)含量、过氧化氢酶活性(CAT)、总抗氧化能力(T-AOC)、谷胱甘肽过氧化物酶活性(GSH-Px)、还原型谷胱甘肽含量(GSH)、氧化型谷胱甘肽含量(GSSG)。结果表明:洛氏鱥肝胰脏的谷草转氨酶(AST)活性随蛋白质水平的升高呈上升趋势,40.01%和44.98%组洛氏鱥肝胰脏中AST活性显著高于24.98%、30.02%和34.99%组(P<0.05),30.02%和34.99%组洛氏鱥肝胰脏的AST活性显著高于24.98%组(P<0.05),30.02%与34.99%组洛氏鱥肝胰脏的AST活性差异不显著(P>0.05),40.01%和44.98%组洛氏鱥肝胰脏的AST活性差异不显著(P>0.05);随着饲料蛋白质水平的升高,洛氏鱥肝胰脏的ALT活性呈上升趋势,且各组间差异显著(P<0.05);洛氏鱥肝胰脏中蛋白酶活性呈先上升后下降趋势,但各组间差异不显著(P>0.05);洛氏鱥前肠和中肠的蛋白酶活性均呈先升高后降低趋势,40.01%组洛氏鱥前肠和中肠蛋白酶活性显著高于24.98%、30.02%和44.98%组(P<0.05),但与34.99%组差异不显著(P>0.05);随着饲料蛋白质水平的升高,洛氏鱥后肠蛋白酶活性呈先上升后下降的趋势,40.01%组洛氏鱥后肠蛋白酶活性显著高于24.98%、30.02%、34.99%和44.98%组(P<0.05)。在试验条件下,随着饲料蛋白质水平的升高,洛氏鱥肝胰脏中MDA含量呈先降低后升高趋势,40.01%组洛氏鱥肝胰脏的MDA含量活性显著低于24.98%、30.02%、34.99%和44.98%组(P<0.05);随着饲料蛋白质水平的升高,洛氏鱥肝胰脏的CAT活性、T-AOC、GSH-Px、GSH含量、GSSG含量呈先增高后降低的趋势,其中40.01%组洛氏鱥肝胰脏的CAT、T-AOC、GSH-Px、GSH、GSSG显著高于24.98%、30.02%、34.99%和44.98%组(P<0.05)。综上,饲料蛋白质水平为40.01%时,洛氏鱥蛋白酶活性及抗氧化酶活性最高。

In order to evaluate the effects of dietary protein levels on protein metabolizing enzyme activity and antioxidant capacity of Rhynchocypris lagowskii Dybowski, in this study, the young fish of Rhynchocypris lagowskii Dybowski[(6.98±0.01)g] was used as research object, fish meal, soybean meal, rapeseed meal and cottonseed meal were used as protein sources and mixed fat[V(corn oil)∶V(fish oil)=1∶1]as fat source to formulate an equal-fat(6.0%) compound feed of 5 protein levels(24.98%, 30.02%, 34.99%, 40.01%, 44.98%) for a 8-week feeding trial.After the feeding trial,Folin-phenol method was used to determine hepatopancrea protease and intestine protease activities, and kits were used to measure AST, ALT, MDA, CAT, T-AOC, GSH-PX, GSH and GSSG activities of hepatopancrea. The results showed that,under the current conditions, with the increase of dietary protein level, AST activities of Rhynchocypris lagowskii Dybowski were increased. AST activities of 40.01% and 44.98% groups were significantly higher than those in 24.98%, 30.02% and 34.99% group(P<0.05). AST activities of 30.02% and 34.99% groups were significantly higher than those in 24.98%group(P<0.05).But the activities of AST of 30.02% and 34.99% groups showed no significant difference(P>0.05). The same results were found in 40.01% and 44.98% groups(P>0.05). With the increase of dietary protein level, ALT activities of Rhynchocypris lagowskii Dybowski were significantly increased(P<0.05).With the increase of dietary protein level, hepatopancrea protease activities of Rhynchocypris lagowskii Dybowski increased first and then decreased, but there was no significant difference among them(P>0.05). With the increase of dietary protein level, protease activities in fore intestine and middle intestine of Rhynchocypris lagowskii Dybowski increased first and then decreased, when the protein level was 40.01%, protease activities in fore intestine protease and middle intestine were significantly higher than those in 24.98%, 30.02% and 44.98% groups(P<0.05), but there was no significant difference with 34.99% group(P>0.05). With the increase of dietary protein level, protease activities in hind intestine of Rhynchocypris lagowskii Dybowski increased first and then decreased, and when the protein level was 40.01%, the protease activities were significantly higher than those in 24.98%, 30.02%, 34.99% and 44.98% groups(P<0.05).With the increase of dietary protein level, MDA content of Rhynchocypris lagowskii Dybowski decreased first and then increased, and when the protein level was 40.01%, MDA content was significantly lower than that in 24.98%, 30.02%, 34.99% and 44.98% groups(P<0.05).With the increase of dietary protein level, CAT, T-AOC, GSH-Px, GSH and GSSG of Rhynchocypris lagowskii Dybowski increased first and then decreased, when the protein level was 40.01%, CAT, T-AOC, GSH-Px, GSH and GSSG activities were significantly higher than those in 24.98%, 30.02%, 34.99% and 44.98% groups(P<0.05).In summary,when the protein level of feed was 40.01%, the activities of protease and antioxidant enzyme in Rhynchocypris lagowskii Dybowski were the highest.