Effects of aging on fat deposition and meat quality in Sheldrake duck

Sheldrake is a duck breed widely used for its meat and eggs. In this study, the quantities of abdominal fat, sebum, intramuscular fat and liver fat, meat quality (pH, cooking loss, drip loss, and shear force), and expression and activity of several enzymes at different ages were determined. The results showed that the fat content increased (P < 0.05) during the aging process (90 d, 180 d, 270 d, and 360 d). Fatty acid synthase (FAS) and malic enzyme (ME) were chosen to represent the activity of lipid biosynthesis in Sheldrake ducks. The quantitative real-time PCR and enzymic activity data showed that the expression of both FAS and ME were generally up-regulated along with aging. Based on these results, the individual ducks were selected at 180 d and 360 d for analyzing the changes of serum lipid levels and related enzymic activities in liver. The contents of triglycerides (TG), total cholesterol (TCH), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) in serum were found not significantly different (P > 0.05). However, we thought that the variation of TG/HDL (P < 0.05) might explain the increased fat deposition. Moreover, the activities of lipoprotein lipase (LPL) and hepatic lipase (HL) were both detected significantly up-regulated at 360 d (P < 0.05). The meat quality results of breast muscles indicated that pH, cooking loss, drip loss, and shear force values could all be affected by aging. Considering these results, we concluded that the best quality of Sheldrake duck meat occurs between 180 d and 270 d. These results might provide useful information for Sheldrake cultivation and research on lipid metabolism.