| These studies were focused on the subject of juvenile hybrid sturgeon, we havestudied the development, feeding, the body component, immunity and bloodbiochemistry changes of hybrid sturgeon who’s initial average weight was38g infour different culture density（40/㎡,70/㎡,93/㎡,110/㎡） on the running waterenvironment, we also examined the water quality relate to the four different density.The result is as follows:The changes of water temperature, pH, ammoniacal nitrogen and COD indifferent density groups were not significant, and DO decreased as the densityincreased and fish grew. After60days experiment span, the specific growth rate,daily weight gain and feeding efficiency decreased as the density increased, the foodconversion efficiency and the net weight increases as the density increases. Thissuggested that high culture density could lead to pond water quality deterioration, soas to threaten fish growth, especially the decrease of OD and the increase of CODand ammoniacal nitrogen.Breeding density of large hybrid sturgeon has an effect on liver body index,condition factor and body components. Hepatosomatic index decreases with thebreeding density increases, but there is no significant difference between the everydensity group. At the end of the experiment the CF of the high density group issignificantly lower than other groups. The body crude protein of juvenile sturgeon,crude fat content decreased with the density increases, At day60, the crude proteinof high-density group fish content was significantly lower than the other threegroups, crude fat content was no significant difference. Carcass moisture and ashcontent are negatively correlated. The high density group was significantly higher incarcass moisture and the ash content has no significant difference. This shows thatthe breeding density change fish nutrients and energy accumulation in the body,causing the body biochemical composition changes, which have an adverse impact on the nutritional status of the fish, but most of this effect began to show late in theexperiment.The high-density breeding model has an effect on immune and bloodbiochemical content of the large juvenile sturgeon. The result shows the spleencoefficient, the number of white blood cells showed a downward trend as the densityincreases, the number of lymphocytes and breeding density form a significantnegative correlation. Glutamic acid amino transferase (ALT) exhibit an upward trendwith increased stocking density, alkaline phosphatase (ALP), total protein (TP),albumin (ALB), total cholesterol (TC), glycerol ester (TG) etc. was negativelycorrelated with breeding density. This may be caused by malnutrition or organdamage as the density increases. The results of serum total protein, albumin, totalcholesterol trend and glycerate fish crude fat are consistent with the results of crudeprotein. This confirms that the high density farming can lead to fish malnutrition,nutritional value and economic value decline, but from the results of thedetermination of fish composition, this trend is usually happened at the late stage ofthe experiments (Section40d). Blood sugar levels showed no significant differencesamong the groups, it may be prolonged metabolic recovery after the longtimemetabolic. The serum level of thyroxine (FT3) increased at first and then shows adownward trend in the whole time. At the end of the experiment, the serum level ofFT3in the low-density group still significantly higher than the other three groups.The result shows that the high-density stress can lead to the decline of FT3in serum,thereby adversely affect the growth and development of fish, which is consistentwith our test results of the growth indicators of juvenile large hybrid sturgeon. |
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