微胶囊蛋氨酸或晶体蛋氨酸对军曹鱼幼鱼相关酶活性的影响

Effect of supplementation microcapsule or crystalline methionine in diets on related enzyme activity of cobia(Rachycentron canadum)

比较研究了低鱼粉饲料中添加微胶囊蛋氨酸或晶体蛋氨酸对军曹鱼（Rachycentron canadum）消化酶和蛋白质代谢酶活性的影响。将鱼粉组和减少鱼粉后蛋氨酸缺乏组分别设为正、负对照组,试验组饲料在负对照组的基础上分别添加晶体蛋氨酸（MET）、羟基蛋氨酸（MHA）、邻苯二甲酸醋酸纤维素微胶囊蛋氨酸（CAP）、丙烯酸树脂微胶囊蛋氨酸（RES）和棕榈酸甘油酯微胶囊蛋氨酸（TPA）,共7组等氮等脂饲料。每个处理设3个重复,每个重复放养20尾鱼,初始体质量（5.40±0.07）g,流水养殖8周,水温29~31℃。结果显示微胶囊蛋氨酸组的军曹鱼肠道胰蛋白酶活性显著高于正对照组和MET组（P〈0.05）,MET和TPA组肝脏谷草转氨酶（GOT）活性显著高于正负对照组（P〈0.05）;MET组军曹鱼幼鱼摄食后0.5 h肠道Na＋、K＋-ATP酶活性显著高于其他各组（P〈0.05）,摄食3 h后正对照组和RES组Na＋、K＋-ATP酶活性上升,显著高于CAP和MHA组（P〈0.05）,摄食8 h后正对照组和微胶囊蛋氨酸组显著高于MHA和MET组（P〈0.05）。以上结果表明,军曹鱼低鱼粉饲料中添加晶体蛋氨酸即可增进氨基酸的代谢和蛋白质的合成,微胶囊有助于蛋氨酸在肠道中的缓慢释放,提高肠道内胰蛋白酶活性。

The present study was conducted to compare the effect of microcapsule methionine or crystalline me-thionine in low-fishmeal diets on protein metabolism and digestive enzyme activities in cobia（Rachycentron ca-nadum）.Seven iso-nitrogen and iso-lipid diets,including fishmeal（positive control）,low-fishmeal（negative con-trol） and five types of methionine supplementation of crystalline L-methionine（MET）,hydroxyl-methionine cal-cium（MHA）,cellolose-acetate-phthalate coated methionine（CAP）,resin coated methionine（RES） and tri-palmitin-polyvinyl alcohol coated methionine（TPA）,respectively were prepared to investigate utilization of coated and crystalline methionine in intestine of juvenile cobia.Each treatment was randomly assigned to triplicate groups of 20 fish with initial weight of（5.40±0.07） g per aquarium.Fish were maintained in flow-through aquaria for eight weeks at water temperature ranged from 29℃ to 31℃.The results showed that trypsin activities of in-testine of fish fed microcapsule methionine were significantly higher than those of fish fed crystalline methionine and the positive control diet（P〈0.05）.Compared to positive and negative groups,fish fed the diets with MET and TPA had significant difference in liver GOT activities（P〈0.05）.After feeding 0.5 h,Na＋,K＋-ATP activities in intestine of fish fed MET were significantly higher than those of fish in other groups（P〈0.05）.After feeding 3 h,Na＋,K＋-ATP activities of fish fed RES and positive control diet increased and was higher than those of fish fed CAP and MHA,and those activities of fish fed positive control diets and microcapsule methionine were signifi-cantly higher than those of fish fed MHA and MET after feeding 8 h（P〈0.05）.It could be concluded that cobia fed low fishmeal diet with crystalline methionine could improve their metabolism of amino acid and synthesis of pro-tein.Microcapsule could contribute to controll methionine release in intestine and enhance the activities of intes-tinal protease.