饲料中不同磷水平对黄鳝生长、体成分及部分生理生化指标的影响

为探讨饲料中不同磷水平对黄鳝幼鱼生长、体成分、骨骼矿化及血液生化指标的影响,以商业配方为基础,磷酸二氢钙为磷源Ca(H2PO4)2],配制磷含量分别为0.67%、0.91%、1.05%、1.29%和1.53%的5种等氮等能饲料。每种饲料投喂3个网箱(1.5 m×2.0 m×1.5 m),每个网箱放养实验鱼初始体质量(34.4±0.3)g]100尾,进行70 d的养殖实验。结果显示:(1)随着饲料中磷含量从0.67%增加到1.05%,黄鳝幼鱼各组增重率(WGR)、蛋白质效率(PER)和饲料效率(FE)显著升高(P0.05),当磷含量高于1.05%后各指标进入平台期。折线模型分析Y=104.67-46.07(1.10-X),R2=0.944]显示,当饲料中磷含量为1.10%时可满足黄鳝生长需要;(2)随着饲料中磷含量的增加,实验鱼体的粗蛋白含量和肥满度显著升高(P0.05),而粗脂肪含量和肝体比显著下降(P0.05);(3)饲料磷含量增加,可显著提高实验组全鱼灰分和全鱼磷含量(P0.05)。折线模型分析Y=0.988-0.635 4(1.05-X),R2=0.928]显示,当饲料中磷含量为1.05%时可满足黄鳝全鱼磷累积需要;饲料磷含量增加也显著提高了脊椎骨钙和磷含量(P0.05),但脊椎骨钙磷比无显著差异。折线模型分析Y=7.696-0.985 5(1.10-X),R2=0.956]显示,当饲料中磷含量为1.10%时可满足黄鳝脊椎磷累积需要;(4)饲料磷水平对血清中的磷和钙含量以及碱性磷酸酶活性有显著影响(P0.05)。研究表明,在本实验条件下,饲料中磷含量为1.10%,可以满足黄鳝对磷最大的组织储存需要以及最佳的生长效果。

Influence of dietary phosphorus levels on growth performance, body composition and biochemical indices of juvenile rice field eel(Monopterus albus)

Phosphorus is one of the most important minerals required by fish.Due to low concentration of phosphorus in natural waters,and low absorption rate of phosphorus from the water,fish must obtain most of phosphorus from their diets.The optimal amount of phosphorus supplementation in commercial feeds is important not only economically,but also for environmental reasons.Phosphorus metabolism in cultured aquatic species has become a popular research subject,due to rising concerns about phosphorus discharged into aquaculture environment.The present experiment was conducted to evaluate the effects of dietary phosphorus on growth performance,body composition,bone mineralization and blood chemistry index of juvenile rice field eel(Monopterus albus).Five practical diets were formulated to contain graded levels(0.67%,0.91%,1.05%,1.29% and 1.53%)of phosphorus from dietary ingredients and monocalcium phosphate.Each diet was randomly fed to triplicate groups of fish with initial mean weight of (34.4±0.3) g in floating cages(1.5 m×2.0 m×1.5 m)to apparent satiation for 70 days,and each cage was stocked initially with 100 fish.The results showed that:(1)fish weight gain rate(WGR),protein efficiency ratio(PER)and feed efficiency(FE)increased with increasing phosphorus from 0.67% to 1.05%(P<0.05)and then plateau over the level of 1.05%.Broken-line analysesY=104.67-46.07(1.10-X),R²=0.944]suggested that optimum dietary phosphorus content is 1.10% based on WGR.(2)whole-body protein contents and condition factor(CF)were significantly elevated,however,whole-body lipid contents as well as hepatosomatic index(HSI)were significantly reduced by increasing dietary phosphorus.(3)Diet phosphorus level can sighnificantly enhance the content of whole-body ash and phosphorus(P<0.05).Broken-line analysesY=0.988-0.635 4(1.05-X),R²=0.928]suggested that fish fed diets with phosphorus of 1.05% presented highest whole-body phosphorus content.both vertebrae phosphorus and calcium contents increased linearly with increasing dietary phosphorus levels while vertebrae Ca/P ratio was not influenced.Broken-line analysesY=7.696-0.985 5(1.10-X),R²=0.956]indicated vertebrae phosphorus content showed highest values at the diet phosphorus of 1.10%.(4)Dietary TP had distinct effects on P,Ca and alkaline phosphatase contents in serum.This research revealed that 1.10% dietary total phosphorus was required for maximal tissue storage and mineralization as well as optimal growth.