| In this paper, the effect of stocking density on water quality, growth performanceand feeding of Amur sturgeon (Acipenser schrenckii) was investigated. Also therelationship between density and nutritive index and blood biochemistry were studiedin this experiment. The juvenile Amur sturgeon with body weight of (225.69±32.28) gwere reared in nine18.23㎡concrete tanks at water14-17℃at initial densities of5.5kg/,8.0kg/m3and11.0kg/m3for70days. The result is as follows:(1) The results showed that there were significant decreases in weight increment,special growth rate, daily weight gain and feeding ratio of the juveniles withincreasing stocking density(P<0.05), but the feed coefficient showed a contrary trend.And the growth efficiency was largest in medium stocking density (MSD,8.0kg/m3).During the experiment, a significant decrease in dissolved oxygen(DO) was observed asstocking density increasing, but ammonia-nitrogen content and chemical oxygenconsumption (COD) were decreased with increasing stocking density(P<0.05).Theseresults suggest growth suppression caused by high stocking density might be relatedto both crowding stress and water deterioration, as well as associated with reductionsin both food consumption and feeding ratio. And8.0kg/m3was considered to be asuitable stocking density for the size of Amur sturgeon.(2) Stocking density has some effect on flesh content, liver body index, conditionfactor and muscle components. At the end of the experiment, flesh content wassignificantly lower in high stocking density (HSD) group than other groups’(P<0.05).the CF of the high density group showed the same trend. Hepatosomaticindex decreases with the stocking density increases, but there is no significantdifference between the every density group. Muscle crude protein and crude fatcontent increased with increasing density at first, but then decreased. which was, while carcass moisture and ash content did not significantly changed. At the end ofthe experiment, crude protein content and crude lipid content in muscles significantlylower in HSD group(P <0.05), but there was no significant difference in moisturecontent and ash content. The results showed that stocking density affected nutrientsand energy accumulation in fish body, therefore, the energy used for growth decreasedand more extra energy consumption were consumed to deal with crowding stress.(3) Stocking density has different effect on blood biochemistry indexes in Amursturgeon. The RBC amount and hemoglobin level increased with the increasingstocking density. The leukocyte amount increased first and then decreased during theexperiment. At the end of the study, leukocyte amount in HSD group weresignificantly lower than other groups’(P<0.05). Serum organic component is alsoaffected by the density, Serum glucose increased slightly with increasing stockingdensity, but the change was not significant; The cholesterol and triglyceride levelswas significantly decreased with the increasing density (P <0.05); Serum total proteincontent was also significantly reduced,which were related to the increased ureanitrogen echoes;The serum ALP activities was the lowest in HSD group, while theserum AST and ALT activities were significantly higher than other groups’(P<0.05).Serum inorganic ions were also affected by stocking density, Magnesium andphosphorus levels significantly decreased with increasing density, and calcium is notchanged significantly. These results indicate that sturgeon in HSD group withstandhigher levels of chronic stress; besides glucose and calcium, other biochemicalparameters of the study can be selected as reflection factors of sturgeon suffer fromchronic stress caused by the stocking density; the test provided reference for screeningfactors of Amur sturgeon against chronic physiological stress. |
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