饲料中苏氨酸含量对建鲤肉质及组织蛋白酶B、L的影响

Effect of dietary threonine supplement on the fillet quality and cathepsin B/L level of Jian carp (Cyprlnus carpio var Jian)

该试验测定了饲料中3组苏氨酸含量,即7.4 g/kg(缺乏组)、15.7 g/kg(适宜组)、25.2 g/kg(过量组),对建鲤肉质及组织蛋白酶B、L的影响。通过利用显微镜图像分析各处理组肌纤维特征、鱼肉品质指标,荧光合成肽底物法测定组织蛋白酶B(cathepsin B,CTS B)、组织蛋白酶L(Cathepsin L,CTS L)的活性,免疫组化法测定蛋白表达量,研究发现,饲喂90 d后,适宜组的肌纤维密度最高,肌纤维平均直径(22.12μm)最小;肌原纤维耐折力(0.1163μm)相对较高,而其断裂指数(A540=59.70)最低;剪切力(0.1684 kg·f)最高,失水率(21.02%)最低,p H值(6.91)最低;组织蛋白酶B、L的酶活性及表达量最低。综上,饲料中添加适宜水平苏氨酸能够改善鱼肉肌纤维特性及硬度品质,为通过营养素水平调节而提高建鲤鱼肉品质提供一定理论依据。

Effect of threonine on meat quality,cathepsin B and cathepsin L in Jian carp was investigated in the presence of three different threonine contents.The muscle fiber characteristic and fish meat quality were analyzed by microscope analysis.The activity of cathepsin B and cathepsin L were detected by using fluorescent synthetic peptide substrate.The protein expression was measured by method of immunohistochemistry.After 90 days of feeding,the suitable group exhibited the highest density of muscle fiber with shortest diameter(22.12μm).The folding strength of myofibril reached to 0.1163μm which was higher than other groups,while a fracture index of 59.70 A540 was observed and which was lower than other groups.Additionally,the suitable group exhibited the highest shear force(0.1684 kg·f).In contrast to that,the lowest of desiccation(21.02%),pH value(6.91)and the activities and expressions of cathepsin B and cathepsin L were observed in the suitable group.In summary,the addition of a suitable level of threonine into the fodder can improve the muscle fiber characteristic and hardness quality of fish.It provides a theoretical basis of nutrient regulation for improving the quality of Jian carp.