许氏平鲉幼鱼对饲料中维生素B6需求量的研究

Dietary Vitamin B Requirements of Juvenile Rockfish(Sebastes schlegeli)

本实验旨在研究饲料中维生素B6含量对许氏平鲉(Sebastes schlegeli)幼鱼生长、体成分、肝脏酶活和转氨酶基因表达的影响,以确定其对维生素B6的需求量。配制6组维生素B6实际含量分别为2.08(对照组)、3.25、4.16、6.32、10.17和31.14mg/kg的实验饲料,饲喂初始体重为(36.35±0.06)g的许氏平鲉幼鱼63 d。结果显示,随着维生素B6含量的增加,实验鱼的增重率(WGR)和特定生长率(SGR)均呈先升高后降低的趋势,4.16 mg/kg组达到最高。4.16 mg/kg组脏体比(VSI)显著高于对照组(P<0.05),3.25~10.17mg/kg组的肝体比(HSI)和肠体比(ISI)显著高于对照组(P<0.05)。3.25~31.14 mg/kg组的肌肉水分含量显著低于对照组(P<0.05),全鱼和肌肉的粗蛋白和粗脂肪均呈先升后降的趋势。肝脏超氧化物歧化酶(SOD)活力先升高后降低,4.16~10.17mg/kg组显著高于对照组(P<0.05);丙二醛含量(MDA)先降低后升高,3.25~31.14 mg/kg组显著低于对照组(P<0.05);肝脏维生素B6含量先升高后平稳;3.25~31.14mg/kg组谷草转氨酶(GOT)和谷丙转氨酶(GPT)活力显著高于对照组(P<0.05)。谷草转氨酶(GOT1和GOT2)基因相对表达量先升后降,3.25~31.14mg/kg组显著高于对照组(P<0.05);谷丙转氨酶(GPT1和GPT2)基因相对表达量先升后降,均在6.32mg/kg组达到最大值;酪氨酸转氨酶(TAT)基因相对表达量先升后降,4.16~10.17 mg/kg组显著高于其他组(P<0.05);丝氨酸转氨酶(SerC)基因相对表达量呈下降趋势,4.16~31.14 mg/kg组显著低于对照组和3.25 mg/kg组(P<0.05)。以WGR、肝脏维生素B6含量和GPT为评价指标,经折线回归分析表明,体重36 g的许氏平鲉幼鱼维生素B6的需求量为3.53~6.32 mg/kg饲料。

This experiment investigated the effects of dietary vitamin B6 content on growth performance,body composition,liver enzyme activities,and transaminase gene expression in juvenile rockfish(Sebastes schlegeli).Six experimental diets were formulated with different levels of vitamin B6:2.08(control group),3.25,4.16,6.32,10.17,31.14 mg/kg.The juvenile rockfish average initial body weight was(36.35±0.06)g.After 9 weeks of treatment,the results showed that,with an increase in dietary vitamin B6 content,the weight gain rate and specific growth rate of the experimental fish initially increased and then decreased,with the largest changes seen in the 4.16 mg/kg group.The viscerosomatic index of the 4.16 mg/kg group was significantly higher than that of the control group(P<0.05).The hepatosomatic and intestine-somatic indexes of the 3.25 to 10.17 mg/kg groups were significantly higher than those in the control group(P<0.05).Muscle moisture content in the 3.25 to 31.14 mg/kg groups was significantly lower than in the control group(P<0.05).Crude protein and crude lipids of the whole fish and muscle showed increasing trends and then decreases.The activity of superoxide dismutase in livers increased at first and then decreased,with the 4.16 to 10.17 mg/kg groups showing significantly higher activity than the control group(P<0.05).Malondialdehyde content also decreased and then increased,with the 3.25 to 31.14 mg/kg group showing significantly lower content than the control group(P<0.05).Liver vitamin B6 content increased at first and then stabilized.The activities of glutamic oxalacetic transaminase and glutamic-pyruvic transaminase in the 3.25 to 31.14 mg/kg groups were significantly higher than in the control group(P<0.05).The relative expression level of GOT1 and GOT2 genes increased at first and then decreased,with the 3.25 to 31.14 mg/kg groups showing significantly lower expression levels than the control group(P<0.05).Relative expression level of GPT1 and GPT2 genes increased at first and then decreased,reaching a maximum in 6.32 mg/kg group.Relative expression of the tyrosine aminotransferase gene increased at first and then decreased,with the 4.16 to 10.17 mg/kg groups showing significantly higher expression levels than the other groups(P<0.05).Relative expression of the serine transaminase gene decreased,with expression levels in the 4.16 to 31.14 mg/kg groups significantly lower than in the control and the 3.25 mg/kg groups(P<0.05).A broken-line regression analysis of the WGR,liver vitamin B6 content,and GPT parameters showed that the dietary vitamin B6 requirement of juvenile rockfish with a body weight of 36 g was 3.52 to 6.32 mg/kg.