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Système d’information sur les ressources alimentaires et d’engrais en aquaculture
 

Rohu - Supplemental feeds & feeding

Supplementary feed is that which is provided to fish to make up the deficit between natural food availability and their nutritional requirement for good growth and production (De Silva, 1993).  In rohu culture, supplementary feeds are required for larval rearing, fingerling production as well as for grow-out in semi-intensive systems. Rice bran and groundnut oil cake at the ratio of 1:1 are most commonly used for rearing larvae to fry and for fingerling production. No supplementary feeds are provided in low input/extensive systems. However, for medium input /semi-intensive systems, irrespective of natural productivity, supplementary feed must be provided. Under experimental conditions, Mitra and Mukhopadhyay (2002) demonstrated that the use of supplementary feeds results in improved nutrient utilization and fish performance.

Despite the availability of several ingredients (Table 9), rice bran and ground nut oil cake are most commonly used as supplementary feeds for rohu at a ratio of 1:1. Mustard oil cake is also used in areas where it is readily available. Although rice bran and groundnut oil cake ratio of 1:1 is recommended, farmers are often constrained by the price of oil seed cake and hence use various other combinations (Nandeesha, 1993). Some farmers use rice bran only, while others vary the oilseed cake content on a seasonal basis (30-40 percent oilseed cake in summer to 10-20 percent during the monsoon season and in winter). To reduce production costs, farmers pay particular attention to maintaining adequate natural pond productivity through fertilization, as a consequence of which supplementary feeding rates can be reduced.  On average, farmers in Andhra Pradesh use 27 tonnes of feed/ha at a food conversion ratio of 2.5-3.5. Some farmers add vitamin and mineral premixes (manufactured for poultry) to their feeds, while others add common salt (NaCl). Gangadhara et al. (2004) reported that the inclusion of NaCl at 1 percent of the diet results in improved growth. 

Wheat bran can be used instead of rice bran and, if available, potato starch can also be added as a carbohydrate source. The use of ingredients of animal origin in grow-out systems is almost non-existent except in experimental studies and for broodstock rearing. A commonly used rohu broodstock feed is comprised of fishmeal (15-20 percent), broken rice (10-15 percent), pulses (15-20 percent), rice bran (20 percent) and oil cake (20-25 percent) (Mukhopadhyaya et al, 2003).