凡纳滨对虾幼体不同培育密度对水质、仔虾生长、免疫和抗逆性能的影响

Effects of breeding densities of Litopenaeus vannamei larvae on water quality,shrimp growth,immunity and stress resistance ability

根据福建凡纳滨对虾(Litopenaeus vannamei)25 m2池育苗的培养密度,设置16万尾/m^3(Ⅰ)、24万尾/m^3(Ⅱ)、32万尾/m^3(Ⅲ)、40万尾/m^3(Ⅳ)和48万尾/m^3(Ⅴ)5组幼体培育密度,分析不同培育密度对水质、仔虾生长、免疫相关因子活性和抗逆性能的影响.实验结果表明:在同一培育密度条件下,水中溶解氧(DO)含量和pH值随幼体的生长(溞状幼体期、糠虾幼体期和仔虾期)显著下降(p<0.05),而活性磷酸盐(PO4^3--P)、硝酸盐氮(NO3--N)、亚硝酸盐氮(NO2^--N)、氨氮(NH^4+-N)含量和化学耗氧量(COD)则显著上升(p<0.05);在不同培育密度条件下,DO含量和pH值随着培育密度的增加而降低,而PO4^3--P、NO3--N、NO2^--N、NH^4+-N含量和COD则随着密度的增加而升高,其中Ⅰ组水质最好,换水率最低,中密度的Ⅱ和Ⅲ组水质略差于Ⅰ组,其各水质因子仅在育苗后期的仔虾P5期时与Ⅰ组差异显著(p<0.05),而高密度的Ⅳ和Ⅴ组水质均较差,且换水率较高,在溞状幼体Ⅱ期时就与Ⅰ组出现显著差异(p<0.05).对虾幼体生长和存活率随培育密度增加而下降,Ⅰ组仔虾的生长和存活率最高.Ⅰ组的饵料投喂量最少,但与Ⅱ和Ⅲ组无显著差异(p>0.05);Ⅴ组的饵料投喂量最多,与其他各组均差异显著(p<0.05).Ⅱ和Ⅲ组仔虾的免疫相关因子总抗氧化力(T-AOC)和超氧化岐酶(SOD)、氧化物酶(POD)、碱性磷酸酶(ACP)、酸性磷酸酶(AKP)的活力较高,并在低温、低氧和低盐应激反应中表现优良.综合上述结果,24万~32万尾/m^3的幼体培育密度较为合适.

According to the breeding densities of Litopenaeus vannamei larval in a 25 m2 seedling-raising pond in Fujian Province,five nauplius densities of 16×104 ind/m^3(GroupⅠ),24×104 ind/m^3(GroupⅡ),32×104 ind/m^3(GroupⅢ),40×104 ind/m^3(GroupⅣ)and 48×104 ind/m^3(GroupⅤ)were set up.The effects of different densities on water quality,growth,immune-related factor activity and stress resistance ability of shrimp larvae were explored in this study.The results showed that the DO contents and pH values decreased with different growth stages of larvae(zoea,mysis and post larvae)(p<0.05),however the contents of PO4^3--P,NO3--N,NO2^--N,NH^4+-N and COD increased under the same density(p<0.05).Under different breeding densities,the DO contents and pH values decreased with increasing breeding density,however the contents of PO4^3--P,NO3--N,NO2^--N,NH^4+-N and COD increased with increasing breeding density(p<0.05).The best water quality and the lowest water exchange rate appeared in GroupⅠ.The water quality of medium-density GroupⅡand GroupⅢwas slightly worse than that in GroupⅠ,with significant difference in the water quality factors from those of GroupⅠonly at post larvae stage 5(P5)(p<0.05).In the high-density GroupⅣand GroupⅤ,the water quality was the worst and the water exchange rate was the highest with significant difference from those of GroupⅠat mysis stagesⅡ(p<0.05).The growth and survival rate of larvae decreased with the increase breeding density.In low-density GroupⅠ,the growth and survival rate of larvae were the highest and the feeding dose was the least but with no significant difference from those of medium-density GroupⅡand GroupⅢ(p>0.05).However,the feeding dose was higher in GroupⅤthan in other groups(p<0.05).The immune-related factors T-AOC and SOD,POD,ACP and AKP activities of shrimp larval were high in medium-density GroupⅡand GroupⅢ,and the stress resistance ability under low temperature,hypoxia and low salt were more excellent(p<0.05).Considering the above results,a suitable breeding density was from 24×104 ind/m^3 to 32×104 ind/m^3.