The VLDLR gene plays important roles in the growth and adiposity in humans and mice. The purpose of this study was to investigate the relationship between VLDLR gene genetic polymorphisms and growth and abdominal fat traits of the Gaoyou domestic duck. A total of 267 Gaoyou ducks were employed for testing. A 18bp deletion was identified in VLDLR signal peptide coding region. The results of χ 2 test suggested that the genotype frequencies of VLDLR signal peptide coding region were not in Hardy-Weinberg equilibrium. Least squares analysis showed that body weight (BW) of -18bp/-18bp genotype ducks was significantly higher than those of other genotypes from six (BW6) (p<0.05) to ten weeks of age (BW10) (p<0.01). The association analysis was performed taken body weight as covariant for abdominal percentage (AFP). Results showed that there was not interaction between genotype (p>0.05) and body weight for AFP and different genotypes had a significant effect on AFP (p<0.05). The results of Bonferroni t-test revealed that the abdominal fat percentage (AFP) of -18bp/-18bp genotype was significantly lower than those of +18bp/-18bp (p<0.05). Preliminary studies have shown that VLDLR may be a candidate gene for the selection for growth and abdominal fat, and the results of the present study indicate that VLDLR strongly influences carcass abdominal fat content of Gaoyou ducks.

In order to investigate the internal flow characteristics and hydraulic stability of vertical submersible pump station in forward and reverse operation, the steady and unsteady three-dimensional numerical simulation of vertical submersible axial-flow pump device was carried out based on CFD and the energy performance of the pump device was predicted. In this paper, the internal flow characteristics of the vertical submersible axial-flow pump device under forward and reverse operation were analyzed, and the optimization of the structure passed by water was carried out to improve the efficiency of the pump device in forward and reverse operation. The results show that the performance of the pump device is good when it is running in the forward direction, the peak efficiency of the pump device is 72.22% and the corresponding head is 4.01 m. When it is running in the reverse direction, the performance of the pump device decreases significantly with the peak efficiency is only 36.03% and the corresponding head is 3.34 m. The hydraulic loss in the dust-pan-shaped conduit is very small in the forward operation, the wellbore conduit is the main factor which affects the efficiency of the submersible axial flow pump device, the loss ratio is 12%–44%. When the pump device is in reverse operation, the hydraulic loss is similar but the hydraulic performance is poor and the hydraulic loss is obviously larger than that in forward operation. A guide plate is added to the dust-pan-shaped conduit at 0.27 D ( D is the nominal diameter of impeller) along the axis direction of the conduit, and a elbow flow conduit with the corner radius R of 0.83 D is selected to replace the wellbore conduit, the bad flow state disappeared and the efficiency of the pump device increased by 5.19% in the forward operation while the efficiency of the pump device increased by 9.62% in the reverse operation.