Grass carp - Supplemental feeds & feeding

Because grass carp feed on macrophytes the nutrient composition of supplemental pellets can be lower than the specific requirements of complete feeds (Guo, 2006). For example, if fed in combination (plant material and pellets) the pellet protein content can be reduced to 25 percent for juvenile grass carp between 30-50 g. Feeding frequency is adjusted according to feed type. When fed on macrophytes or duckweed grass carp feed for almost 24 hours a day, while only a quarter of the diel cycle is devoted to feeding when fed with pellets or animal based diets (Cui et al., 1995).  Feeding rate should also be adjusted according to temperature and body size. Meat quality can be improved by combination feeding (40 percent pellets and 60 percent macrophytes (Feng et al., 2006b). Farmers often feed their fish with vegetable matter in the morning and with pellets in the afternoon (Wang and Zhang, 2005) and this leads to higher profit margins (Table 7) (Lu and Deng, 2003). Generally, pellets are fed twice a day at 3.5-5.0 percent of body weight per day and grass is fed at 20-30 percent of body weight per day. Feeding the fish at 80 percent of satiation is optimal and results in better feed conversion (Mao, 2006).