Effects Of Different Density On The Growth And Physiological And Biochemical Indexes In Hybrid Sturgeon

In this research, large size hybrid sturgeons(Huso sturgeon♀×Amur sturgeon♂with an initial body weight of243g each) were used as experiment materials to studythe effect of four groups of breeding density(SD1[6kg/m~3], SD2[9kg/m~3],SD3[12kg/m~3], SD4[15kg/m~3]) on feeding behaviors, growth indicators, serumbiochemical indices and muscle component of hybrid sturgeons. After a70-dayfeeding experiment, the results were as follows:1. The breeding density has effect on behavior of hybrid sturgeons. sturgeons inlow density cluster less, most of which live in the water bottom with a light bodycolor,while sturgeons in high density, with a dark body color, collide and tend toavoid colliding. No significant changes were found in the effect on relative fatness ofhybrid sturgeons. The specific growth rate and growth efficiency of sturgeons in SD2group (9Kg/m~3) reaches the maximum, which decreased as breeding density increased.Excessive stocking density, increasing the cost of breeding, not only have a health riskon fish but also may cause the waste of feed, indeed.2. Under different breeding density, the erythrocyte number and hemoglobinconcentration of hybrid sturgeons in low density group increased as the stockingdensity increased while that in high density group decreased significantly. No obviousdifference was found in leukocyte count, inferred that due to hypoxia stress caused bydensity effect, sturgeons were prompted to produce more erythrocyte and hemoglobinin order to increase oxygen-carrying capacity to resist density stress. With theincreasing of breeding density, Glucose and total cholesterol concentrations decreasedgradually while breeding density elevated. However, No obvious difference wasfound in total protein concentrations among four groups. Decreasing glucoseconcentrations, caused by needs of more energy to overcome stress, may promote the decomposition of glucose and cholesterol. Thus, comprehensive study showed thathigh density stress had a negative impact on the growth of fish.3. Crude protein and crude fat content of muscle component decreased asbreeding density become higher. In contrast, ash and moisture increased significantly.Organic matter decreased with elevating organic matter concentration as densityincreased. This indicated sturgeons used organic matter which consumed energy a lotwhen they were faced with density stress. Fat was prior to be used to provide energyso that crude fat concentration changed significantly. No significant changes werefound in crude protein concentration because protein stored in vivo was hardlyconsumed.