Commercial Prawn Production
Feeds and Feeding
Broodstock should be fed a high quality diet containing at least 35% crude protein, a high level of energy, 3.0 kcal/g (85 kcal/oz), and at least 0.5% highly unsaturated fatty acids (a commercially available salmonid fish diet would be suitable). The feeding rate should be equivalent to 1-3% of their body weight per day, and that amount should be divided into two separate feedings of equivalent amounts. Tanks or raceways that hold broodstock should be equipped with structures that will allow maximum use of the entire water column. A few weeks before the eggs achieve a stage of development that is close to hatching, supplemental beef liver should be fed at an equivalent ration on a dry weight basis (moisture content of beef liver = 80%). The frozen beef liver should be cut into half-inch pieces and rinsed with water to remove excess blood that might cause fouling of the system.
No nutritionally complete, formulated diet is currently available to achieve consistently successful larval culture of M. rosenbergii. Therefore, live food is required and newly hatched nauplii of Artemia (brine shrimp) have been the overwhelming choice for use as a nutritionally complete diet. Artemia are available as cysts (dormant unhatched eggs) from a variety of commercial sources. Newly hatched Artemia with an undigested yolk sac are an excellent source of nutrition. After the cysts have been sterilized, and fully or partially decapsulated, they should be hatched under clean conditions to prevent newly hatched nauplii from being a potential source of disease organisms when added to the larval culture tank
Most prawn larvae begin feeding one day after hatching (larval stage 2). Frequent feedings of live food from sunrise to sunset, rather than one or two feedings spread over a long interval of time, should be practiced. Without frequent feedings the nutritional value of uneaten Artemia in the water column decreases over time because the nutrients contained in the yolk sac are continually being removed to satisfy growth and metabolic needs.
Suggested daily feeding rates of nauplii are based on days post stocking and stage index. The initial morning feeding should consist of 40% of the total number of Artemia to be fed that day (daily ration), followed by 20% of the ration later in the morning. The remaining 40% of the daily ration is fed during the afternoon.
A supplemental diet is usually fed during mid-morning and late afternoon, approximately 7-10 days after a postlarval production cycle begins. The ingredient composition of a typical supplemental diet is fish or squid, chicken eggs, beef liver powder, and a marine fish oil that is a good source of highly unsaturated fatty acids.
Juvenile prawns stocked into earthen growout ponds at the previously stated densities initially satisfy their nutritional requirements from consumption of natural pond biota, such as insect larvae and worms. A variety of feeding practices involving the provision of different nutrient sources at different times during growout has been evaluated. However, for the range of stocking densities previously recommended, commercially available sinking channel catfish feed (32% crude protein) has been determined to be an effective diet throughout the growout phase. Recommended feeding rates are based upon estimated survival, estimated consumption expressed as a percent of live body weight, and the mean weight of the population derived from sampling of ponds. See larger table.
A large proportion of the feed is presumed to be not directly consumed by the prawns but rather to serve as a direct source of nutrients for the populations of natural food organisms. A 1% mortality within the pond population is assumed per week, and at the end of the pond growout season, survival generally ranges from 60 to 85% when proper water quality is maintained through recommended management practices (see water quality management section). Yields typically range from 670 to 1,350 kg/ha (600 to 1,200 lb/A). Mean individual weight is inversely related to production and ranges from 28 to 65g or 36-15 prawns/kg (16-7 prawns/lb).
MSU Publications & Information
Other Freshwater Prawns Information