Grass carp - Nutritional requirements

The major nutrient requirements of grass carp have been defined and a China National Recommended Standard has been developed (SC/T 1024-1997) (Table 4, and Table 5), while Table 7 summarizes the dietary requirements for juvenile and on-growing grass carp in a complete diet. Similar to other species, juvenile grass carp require more protein, lipid and energy than larger fish. The protein requirement of grass carp is a function of protein quality, fish size, physiological condition, temperature, availability of natural food, stocking density, ration size and non-protein energy levels (C.X. Ai, unpublished). Juvenile grass carp require approximately 42 percent dietary protein (Dabrowski, 1977), while fish with an initial body weight of 990 g require between 30-35 percent (Khan et al., 2004). Liu and Ren (1995) recommend a dietary lipid for juvenile grass carp (initial body weight 4-7 g) of 8.8 percent, although Du et al. (2005) reported that 4 percent dietary lipid could meet the requirements of juvenile grass carp with an initial body weight of 6.5 g.

The optimum dietary lysine requirement for juvenile grass carp (3-4.4 g) ranges between 1.61 percent (Huang et al., 2003) and 2.24 percent of the dry diet (Wang et al., 2005), which corresponds to around 6 percent of dietary protein. Vitamin E and K3 requirements are 200 mg/kg and 1.9 mg/kg of the diet (Takeuchi et al., 1992; Jiang et al., 2007), while dietary calcium and phosphorus requirements were 0.473-0.788 percent and 1.419-1.577 percent of the diet, respectively (Wang et al., 2002). Su et al. (2007) reported that 300 mg Fe/kg diet resulted in improved weight gain, feed conversion, protein efficiency ratio and protein retention, and Wang and Zhao (1994) recommend a dietary manganese requirement of approximately 15 mg/kg diet.