锰源和锰水平对斜带石斑鱼幼鱼生长、抗氧化功能和矿物元素沉积的影响

Effects of manganese sources and dietary manganese level on growth performance,antioxidative function and tissue mineral accumulation in grouper Epinephelus coioides

为研究甘氨酸锰(GMn)和羟基蛋氨酸锰(HMn)对斜带石斑鱼Epinephelus coioides幼鱼生长、抗氧化功能和矿物元素沉积的影响,在基础饲料中添加0、2、4、8、16、32 mg/kg(以锰计)的甘氨酸锰或羟基蛋氨酸锰分别制成11种试验饲料,在水温为(28±2)℃条件下,投喂初始体质量为12.26 g的斜带石斑鱼幼鱼8周。结果表明:(1)对照组(不添加锰)的增重率(WGR)显著低于锰添加组(P<0.05),两个锰添加组的WGR均随锰添加量的增加逐渐升高后趋于稳定;以WGR为判据,通过折线模型分析表明,以GMn和HMn为锰源时,石斑鱼对饲料中锰的最适需要量分别为9.04、12.87 mg/kg,GMn的生物利用率相当于HMn的1.78倍。(2)石斑鱼肝脏中锰超氧化物歧化酶(Mn-SOD)活性随着锰添加水平的增加先升高后下降,丙二醛(MDA)含量随着锰添加水平的增加而减少;以肝脏Mn-SOD活性为判据,通过一元二次回归方程分析得出,以GMn和HMn为锰源时,石斑鱼对饲料中锰的最适需要量分别为21.15、20.61 mg/kg。(3)石斑鱼脊椎骨和全鱼的锰含量随饲料中锰含量的升高而显著增加(P<0.05);对照组脊椎骨的铁含量显著高于锰添加组(P<0.05),脊椎骨和全鱼的铁含量随饲料中锰含量的升高而显著减少(P<0.05)。研究表明,当饲料中锰含量满足斜带石斑鱼幼鱼生长需要时,进一步补充有机锰源对其生长性能无显著影响,甘氨酸锰的生物利用率高于羟基蛋氨酸锰,而两种锰源的抗氧化能力相似。

The effects of dietary organic manganese sources and level on growth performance,antioxidative function and tissue mineral accumulation were investigated in grouper Epinephelus coioides with initial body weight of 12. 26 g. The grouper juveniles were fed eleven experimental diets supplemented with the graded levels of glycine manganese and manganese 2- Hydroxy- 4-（ methylthio） butyrate at a dose of 0,2,4,8,16 and 32 mg Mn / kg diet to satiation at water temperature of（ 28 ± 2） ℃ for 8 weeks. There was significantly lower weight gain rate（ WGR） in the control group than in the Mn supplemented groups（ P〈0. 05）,in which the WGR was shown to be increased at first with the increase in manganese level,then to stable level. The requirement of juveniles for dietary manganese was estimated to be 9. 04 mg / kg in glycine manganese and 12. 87 mg / kg in manganese 2- Hydroxy- 4-（ methylthio） butyrate using the broken- line model with WGR as the dependent variables,the biological utilization of glycine manganesas being as high as 1. 78 times as manganese 2- Hydroxy- 4-（ methylthio） butyrate in terms of WGR. The activities of Mn- SOD in the liver were found to be increased with elevated supplementation of dietary Mn,and the MDA contents in the liver decreased with the increasing dietary Mn level. The nonlinear model based on quadratic polynomial regression equations,with Mn- SOD as the dependent variables,revealed that the requirement of juveniles for dietary manganese was estimated to be 21. 15 mg / kg in glycine manganese and 20. 61 mg / kg in manganese 2- Hydroxy- 4-（ methylthio） butyrate. The manganese contents of vertebrae and whole fish were found to be increased significantly with increase in supplementation of dietary Mn（ P〈0. 05）. However,the Fe contents of vertebrae and whole fish were significant decreased with increase in supplementation of dietary Mn（ P〈0. 05） when supplementation of dietary Mn. In conclusion,further addition of Mn did not lead to elevated growth in the grouper fed the diet containing enough Mn. But on the growth performance of grouper,the bioavailability of glycine manganese was found to be higher than the manganese 2- Hydroxy- 4-（ methylthio） butyrate,both showing the similar level of antioxidation ability.