吉富罗非鱼对饲料中维生素B_2的需要量

本试验旨在确定吉富罗非鱼对饲料中维生素B_2的需要量。以酪蛋白、明胶和糊精等为主要饲料原料,配制维生素B_2含量分别为0.4、2.6、5.4、10.8、20.4、39.7 mg/kg的6种试验饲料,在室内循环水养殖系统中分别投喂初始体质量为(59.5±0.9)g的吉富罗非鱼10周,每种饲料投喂3个重复,每个重复放养15尾吉富罗非鱼。养殖试验结束后测定吉富罗非鱼的生长性能、肝脏维生素B_2含量和部分血清生化指标等。结果表明:吉富罗非鱼的增重率随饲料中维生素B_2含量的增加先呈线性增加,在达到10.8 mg/kg后趋于稳定,饲料效率的变化趋势与增重率类似;10.8、20.4、39.7 mg/kg组脏体比显著高于0.4、2.6 mg/kg组(P0.05);10.8、20.4、39.7 mg/kg组肝体比显著高于0.4 mg/kg组(P0.05);饲料中维生素B_2含量对肥满度无显著影响(P0.05)。随着饲料中维生素B_2含量的增加,全鱼粗脂肪含量呈先增加后降低的趋势,5.4 mg/kg组显著高于其他各组(P0.05);全鱼水分含量以5.4 mg/kg组最低,显著低于除39.7 mg/kg组外的其他各组(P0.05);全鱼粗蛋白质含量以39.7 mg/kg组最高,显著高于除5.4 mg/kg组外的其他各组(P0.05);各组之间全鱼粗灰分含量无显著差异(P0.05)。饲料中维生素B_2含量对肌肉和肝脏水分、粗蛋白质、粗脂肪含量均没有显著影响(P0.05)。肝脏中维生素B_2含量随饲料中维生素B_2含量的增加而增加,在达到20.4 mg/kg后趋于稳定;0.4 mg/kg组的血清总胆固醇、甘油三酯含量及谷丙转氨酶和谷草转氨酶活性显著高于其他各组(P0.05)。折线模型分析表明,吉富罗非鱼获得最佳生长速度和最大肝脏维生素B_2蓄积量时,其对饲料中维生素B_2的需要量分别为10.2和19.3 mg/kg。

Dietary Vitamin B2 Requirement of Genetically Improved Farmed Tilapia ( Oreochromis niloticus)

The present study was conducted to determine the dietary vitamin B2 requirement of genetically im-proved farmed tilapia ( GIFT, Oreochromis niloticus) . Six experimental diets were formulated to contain 0.4, 2.6, 5.4, 10.8, 20.4 and 39.7 mg/kg vitamin B2 using casein, dextrin and gelatin as chief feed sources, re-spectively. Each diet was assigned to three replicates of 15 GIFT [initial body weight=(59.5±0.9) g] which were cultured in recirculating aquaculture system for 10 weeks, and the growth performance, liver vitamin B2 content, some serum biochemical indices, etc. of GIFT were determined after the cultural experiment. The re-sults showed as follows: with the increase of dietary vitamin B2 content, the weight gain rate of GIFT first in-creased linearly and then remained nearly unchanged when dietary vitamin B2 content came up to 10.8 mg/kg. The results of feed efficiency showed the similar tendency with the result of weight gain rate. Viscerosomatic index in 10.8, 20.4 and 39.7 mg/kg groups were significantly higher than that in 0.4 and 2.6 mg/kg groups (P<0.05), and the hepatosomatic index in 10.8, 20.4 and 39.7 mg/kg groups was significantly higher than that in 0.4 mg/kg group (P<0.05). No significant difference was observed in condition factor among all groups ( P>0.05) . With the increase of dietary vitamin B2 content, the crude lipid content in whole fish was firstly increased and then decreased, and it in 5. 4 mg/kg group was significantly higher than that in other groups ( P<0.05) . The moisture content in whole fish in 5.4 mg/kg group was the lowest, which was signifi-cantly lower than other groups except 39.7 mg/kg group ( P<0.05) . The crude protein content in whole fish in 39.7 mg/kg group was the highest, which was significantly higher than other groups except 5.4 mg/kg group ( P<0.05) . Dietary vitamin B2 content had no significant effects on the content of ash in whole fish and the contents of moisture, crude protein, crude lipid in muscle and liver ( P>0.05) . With the increase of dietary vi-tamin B2 content, the content of vitamin B2 in liver increased linearly until came up to 20.4 mg/kg, and then hold steady. The contents of serum total cholesterol and triglyceride and the activities of serum aspartate amin-otransferase and alanine aminotransferase in 0. 4 mg/kg group were significantly higher than those in other groups ( P<0.05) . Broken-line model analysis indicates that the dietary vitamin B2 requirement of GIFT is esti-mated to be 10.2 mg/kg for maximum growth rate, and 19.3 mg/kg for maximum vitamin B2 accumulation in liver, respectively.