大黄鱼幼鱼对饲料硒的需求量

为确定大黄鱼(Larimichthys croceus)对饲料硒的需求量, 以Na2SeO3为饲料硒源, 配制6种饲料, 硒的添加水平分别为0(对照组)、0.05、0.2、0.4、0.6和0.9 mg/kg, 实测值分别为0.08、0.16、0.27、0.44、0.66和0.96 mg/kg。在海水浮式网箱中养殖初始体重为(9.140.09) g的大黄鱼幼鱼10周, 结果表明增重率(WG)、全鱼和骨骼中的硒含量随着饲料硒含量的升高而显著升高(P0.05)。当饲料硒含量分别超过0.27、0.66、0.66 mg/kg时, 这些指标的变化趋于平稳。饲料硒含量对存活率(SR)、饲料效率(FE)、体组成、肝体比(HSI)、脏体比(VSI)和肥满度(CF)都没有显著影响(P0.05)。在血清中谷胱甘肽过氧化物酶(GPX)活性、超氧化物歧化酶(SOD)活性和总抗氧化力(T-AOC)随着饲料硒含量的升高呈现先升高后稳定的趋势(P0.05), 并分别在饲料硒含量为0.44、0.44、0.16 mg/kg时达到最大值。肝脏中GPX活性、SOD活性、T-AOC、过氧化氢酶(CAT)活性和谷胱甘肽还原酶(GR)活性与血清中相应酶的活性有相同的趋势。在肝脏中谷胱甘肽硫转移酶(GST)活性随着饲料硒含量的升高呈现先降低后升高的趋势(P0.05), 并在饲料硒含量最高(0.96 mg/kg)时其活力取得最大值。以WG为评价指标, 得出大黄鱼幼鱼对饲料中硒的需求量为0.178 mg/kg。以全鱼和骨骼中硒含量、肝脏GPX活性为评价指标, 得出大黄鱼幼鱼对饲料中硒的最小需求量分别为0.575、0.387和0.440 mg/kg。  

DIETARY SELENIUM REQUIREMENT OF JUVENILE LARGE YELLOW CROAKER LARIMICHTHYS CROCEUS

To study the effects of selenium to the juvenile large yellow croaker Larimichthys croceus, six experimental diets were formulated to contain the following diets with increment levels of selenium 0 (control), 0.05, 0.2, 0.4, 0.6 and 0.9 mg/kg, respectively. The final content of selenium in each diet was 0.08, 0.16, 0.27, 0.44, 0.66, and 0.96 mg/kg, respectively. Each diet was randomly assigned to triplicate groups of 60 large yellow croaker juveniles initial body weight: (9.14 0.09) g. Fish were fed twice daily (5:00 and 17:30) to satiation for 10 weeks. The results showed that the weight gain rate (WG), whole-body, and vertebrae Se concentration significantly increased with the increased dietary selenium levels (P0.05), and no further increases when the dietary Se concentration was 0.27 mg/kg or higher in the diet. No significant differences were found in the survival rate (SR), feed efficiency (FE), body compositions, hepatosomatic index (HSI), viscerosomatic index (VSI), and condition factor (CF) cross the 6 treatment groups (P0.05). The serum glutathione peroxidase (GPX) activity, superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC) significantly increased with the increasing of dietary selenium levels (P0.05) with the highest activities at 0.44 mg/kg and 0.16 mg/kg of dietary selenium, respectively. The GPX activity, SOD activity, T-AOC, catalase (CAT) activity, and glutathione reductase (GR) activity in liver had a similar trend with serum enzyme activity. The liver glutathione S-transferase (GST) activity significantly decreased with the increasing of dietary selenium levels (P0.05), and then increased (P0.05). The highest activity was found in the highest Se level (0.96 mg/kg). Based on WG, the dietary Se requirement of juvenile large yellow croaker was 0.178 mg/kg. Based on the whole-body and vertebrae Cu concentration, liver GPX activity, the minimum dietary Se requirements were 0.575, 0.387 and 0.440 mg/kg, respectively.