| In this study, the liver weight, body weight, and body size of84-day old black Muscovy ducks were measured before or after overfeeding with high energy feed. The correlations between liver weight, body weight, and size were analyzed, which could provide a foundation for selection for high-yield fatty liver ducks. Moreover, blood biochemical variables and nutritious components of fatty liver were also measured during early, middle and late times of overfeeding. Liver sections were compared between the overfeeding group and the control group at the end of overfeeding. This analysis may promote understanding of the effects of overfeeding on blood biochemical variables and nutritious components of fatty liver and provide a molecular basis for the selection for high-yield fatty liver ducks. At last, six genes associated with lipid metablism were determined for their expression levels in the breast, thigh and liver, which may help identify the mechanism underlying the development of fatty liver in ducks.. The results of this study were described in detail as follows:1ã€After16days of overfeeding, liver weight was350g and216.58g, and the ratio of liver weight to body weight was8.11and6.22in male and female Muscovy ducks, respectively. The difference in fatty liver production performance between sexesin black Muscovy ducks was statistically significant. By analysis on the correlation between body weight, body size and fatty liver production performance,we found that the weight, tibia circumference, chest width, breast bone length and half divemaster before overfeeding were significantly correlated with fatty liver production performance, and thus these variables could be used as selective indexes for fatty liver production performance in black Moscovy ducks.2ã€Changes in blood biochemical parameters may reflect metabolism in liver. In this study, fthe concentrations of ALT, AST, VLDL and TG in plama were significantly increased with time of overfeeding and significantly higher in the overfeeding group than the control group at the end of overfeeding. The significant increase may indicate hepatocytes were damaged during the time of overfeeding. Moreover, plasma CHO concentration was significantly elevated during overfeeding, and HDL concentration had a trend of increase. In contrast, the concentrations of LDL and ApoB were on a declining curve. The correlation analysis indicated that there were negative correlation between the indexes of fatty liver production performance and plasma ApoB/LDL concentrations were negatively correlated, however, there were positive correlation between the indexes of fatty liver production performance and the GGT/CHO/ALT concentrations. Together, these results suggested that plasma ALT concentration could be used as a primary indicator for the fatty liver production performance of black Muscovy ducks, and the plasma CHO, GGT, LDL and ApoB concentrations could be used as secondaryindicators.3ã€In this study, the data indicated that, no matter with sex, the moisture of breast muscle, and the protein and fat contents of the liver in the overfeeding group of black Muscovy ducks were significantly higher than the control group. The histological analysis on liver tissue sections showed that the hepatocytes in the overfed black Muscovy ducks were swollen, and the cytoplasm in the hepatocyte was filled with different sizes of lipid vesicles and droplets with round shape and clear boundary. Some lipid droplets were large enough to occupy the position of entire cytoplasm and push the nuclei of hepatocytes to the cell boundary.4ã€Compared with the control group, the overfeeding group at the end of overfeeding was was significantly high in the aboundance of liver FAS, ACC and GPAT, but significantly low in the aboundance of liver MTTP and ApoB. Moreover, overfeeding promoted the expression of lipid metabolism-related genes in the breast and leg muscles of black Muscovy ducks, in particular, the expression of MTTP gene was significantly increased by overfeeding. As the extension of overfeeding time, the expression levels of the lipid metabolism-related genes abovemention were all increased, however, the inereased magnitude of MTTP and ApoB were lower than those of TG-synthesis related genes, which might result in the synthesis of TG overpassing the secretion of TG in the liver, thus leading to the formation of the fatty liver. |
