大口黑鲈幼鱼对饲料中锰的需求量

为确定大口黑鲈幼鱼对饲料中锰的需求量，在含锰5.2 mg/kg的半精制饲料中分别添加0、4、8、16、32和64 mg/kg锰(以MnSO₄·H₂O形式)，制成6种不同锰水平的饲料(5.2、9.6、13.5、20.7、 38.3和67.9 mg/kg)，投喂初始体重(16.00±0.07) g的大口黑鲈幼鱼10周。结果显示，在基础饲料中添加锰，可显著提高大口黑鲈幼鱼的增重率，降低饲料系数，各组增重率与饲料系数在锰含量达到13.5 mg/kg后基本稳定。随饲料中锰含量的增加，血清T-SOD、Mn-SOD活性和全鱼、脊椎骨中的锰含量上升，并在饲料锰含量达到20.7mg/kg后趋于稳定，而血清丙二醛含量则表现为下降的趋势。全鱼铁、骨铁、骨锌和全鱼锰沉积率随饲料锰含量的增加而下降。研究表明，在半精制饲料中补充锰可以促进大口黑鲈幼鱼生长、提高饲料利用率、血清抗氧化能力、全鱼和骨锰的沉积。以增重率、饲料系数、全鱼锰和骨锰为评价指标，经折线回归分析，大口黑鲈幼鱼对饲料中锰的需求量分别为18.3、20.5、21.1和23.4 mg/kg干物质。

Dietary requirement of Mn for juvenile largemouth bass (Micropterus salmoides)

To determine the dietary manganese (Mn) requirement of juvenile largemouth bass, Micropterus salmoides, 0, 4, 8, 16, 32 and 64 mg/kg Mn were added as the form of MnSO4.H2O into the semi-purified diet containing 5.2 mg/kg Mn, to obtain six diets containing Mn of 5.2, 9.6, 13.5, 20.7, 38.3 and 67.9 mg/kg, respectively. Largemouth bass with initial body weight of (16.0±0.5) g were fed one of the six diets for 10 weeks. The results showed that adding Mn to the basal diet significantly increased the weight gain (WG), and reduced feed conversion ratio (FCR) of largemouth bass (P<0.05), which tended to stabilize when dietary Mn reached 13.5 mg/kg. With the increase of dietary Mn, the serum activity of T-SOD and Mn-SOD, and Mn content in whole fish and vertebrae increased, and then kept relatively stable when dietary Mn reached 20.7 mg/kg, but the serum MDA content showed a decreasing trend. In addition, the iron content in whole body, iron and zinc contents in vertebra, and the Mn retention in whole body decreased with the increasing dietary Mn. In conclusion, the supplementation of Mn in semi-purified diet improved the weight gain and feed utilization, promoted serum antioxidant capacity and the Mn retention in whole body and vertebra. Based on the WG, FCR, Mn in whole body and vertebra, the broken-line analysis indicated that the dietary requirement of Mn for largemouth bass was 18.3, 20.5, 21.1 and 23.4 mg/kg dry matter, respectively.