黄颡鱼幼鱼植物性蛋白饲料中添加柠檬酸替代磷酸二氢钠合适水平的研究

Replacement of inorganic phosphorus by citric acid for juvenile yellow catfish Pelteobagrus fulvidraco fed with plant-protein based diets

本实验探究黄颡鱼幼鱼植物性蛋白基础饲料中添加柠檬酸替代磷酸二氢钠的合适水平。共设置7个处理组：阳性对照组DP（只添加Na H2PO420 g/kg）和阴性对照组DN（不添加柠檬酸和Na H2PO4）;实验组D0（柠檬酸2 g/kg＋Na H2PO420 g/kg）、D25（柠檬酸2 g/kg＋Na H2PO415 g/kg）、D50（柠檬酸2 g/kg＋Na H2PO410 g/kg）、D75（柠檬酸2 g/kg＋Na H2PO45 g/kg）、D100（柠檬酸2 g/kg）。实验组中柠檬酸替代Na H2PO4的比例分别为0%、25%、50%、75%和100%,分别饲养初始规格为（3.5±0.1）g的黄颡鱼,每个处理组3口缸,每缸50尾,投喂8周。实验结束后,对鱼体生长性能、营养物质的表观消化率、全鱼营养成分、脊椎骨元素含量、抗氧化性能等指标进行分析。结果显示：（1）饲料中添加柠檬酸替代磷酸二氢钠实验组与阴性对照组相比,显著提高了黄颡鱼的末体质量、增重率、特定生长率,降低了饵料系数,但与阳性对照组相比差异不显著。替代比例为0%~50%时,生长表现最好;（2）实验组中柠檬酸替代磷酸二氢钠与阴性对照组相比,显著提高了干物质、蛋白质以及磷的表观消化率,降低了粪便N和P的含量,与阳性对照组相比差异不显著,且替代比例越高,粪便中N和P含量越低;（3）实验组中添加柠檬酸替代磷酸二氢钠对全鱼水分、粗蛋白、粗脂肪、灰分含量无影响（P〉0.05）;但与阴性对照组相比显著提高鱼体Ca、M g、P、Cu的储积量（P〈0.05）,且随着替代水平的增加呈降低趋势,在0%~75%替代水平储积量最高;脊椎骨各元素含量与阴性对照组相比有所提高,但在替代组与对照组间无显著性差异;（4）柠檬酸替代无机磷在25%~75%水平与阴性对照组相比,显著增强了过氧化氢酶、超氧化物歧化酶、碱性磷酸酶的活性,但对丙二醛、免疫球蛋白M、血磷和血钙的含量无影响。综上所述,为保证鱼体正常生长,减少养殖环境污染,降低饲料成本,在当前基础配方下,黄颡鱼饲料中添加柠檬酸替代磷酸二氢钠的水平可为25%~50%。

A feeding trial was conducted to evaluate the optimum ratio at which dietary sodium dihydrogen phosphate（ Na H2PO4） was replaced with citric acid in the diets of juvenile yellow catfish Pelteobagrus fulvidraco. Seven diets were formulated： positive control group（ DP） that contained only 2% Na H2PO4 and negative control group（ DN） that consisted of neither Na H2PO4 nor phytase; and five treatment groups supplemented with 2 g / kg citric acid and 20,15,10,5,0 g / kg concentrations of Na H2PO4. Thus,dietary Na H2PO4 was replaced with citric acid at ratios of 0%,25%,50%,75%,and 100%,respectively. The groups were desjgnated as D0,D25,D50,D75,and D100. Triplicate tanks were each filled with 50 juvenile ind.（ 3. 5 ± 0. 1） g,which were fed with one of the seven experimental diets. After eight weeks,growth performance,apparent digestibility,body proximate composition,vertebra minerals and antioxidative capacity were investigated. The results show ed that：（ 1） Citric acid supplementation enhanced weight gain and specific growth rate,reduced the feed conversion ratio compared with the negative group,but there were no significant differences with the positive group.;（ 2） Citric acid supplementation significantly enhanced the apparent digestibility of dry matter,protein and phosphorus and decreased fecal phosphorus and nitrogen content compared with negative group,while no significant difference with the positive group. The content of fecal nutrients decreased with the increasing of replacing level;（ 3） there were no differences among control groups and treatment groups in body moisture,crude protein,crude lipid and ash（ P〉0. 05）. Compared with the negative control,citric acid supplementation significantly improved the retention of Ca,M g,P and Cu in the whole body. The highest retention of these nutrients was observed betw een 25% and 75% replacement levels.（ 4） Antioxidant enzymes activity（ CAT,AKP and SOD） reached the highest between 25% and 75%replacement levels compared with the negative group while no differences were observed in serum M DA and Ig M content. In conclusion,in order to reduce nitrogen and phosphorus output in the aquaculture water bodies,the replacing level of sodium dihydrogen phosphate with citric acid in yellow catfish diet betw een 25% and50% will not affect fish growth performance and will help to improve nutrients utilization under the current conditions.