Effects of prawn stocking density and feeding management on rice-prawn culture

摘要

The effects of prawn (Macrobrachium rosenbergii) stocking density and the use of commercial diet on rice-prawn culture were evaluated. The experimental design was completely randomized in a 2 x 2 factorial, with a control (rice monoculture, RM) and four replicates for each treatment. The treatments were: 2 prawns m(-2) without feed (2W), 2 prawns m(-2) with feed (2F), 5 prawns m(-2) without feed (5W) and 5 prawns m(-2) with feed (5F). Mean survival varied from 17.2 +/- 9.3% (5F) to 39.2 +/- 14.9% (2F), and mean weight from 20.3 +/- 2.2 g (2W) to 25.7 +/- 5.85 g (2F). Prawn productivity ranged between 118 +/- 58 kg ha(-1) (2W) and 224 +/- 46 kg ha(-1) (5W). No significant interactions were observed between feeding management and densities. Survival rate was significantly higher (P 0.05) for the 2 prawn m(-2) density while the other variables did not vary significantly among treatments. Rice yields were not statistically different among treatments and varied from 4608 +/- 1225 kg ha(-1) (2F) and 5620 +/- 1202 kg ha(-1) (RM). The results indicate that the rice-prawn system is technically feasible and does not need the addition of commercial diet. Economic analysis showed that stoking 5 prawns m(-2) was not profitable. Total production costs and gross revenue were US$ 1337.84 and US$ 1182.07 for rice monoculture and US$ 2655.60 and US$ 2738.70 for the rice-prawn system(2 prawns m(-2); without feed), respectively. Therefore, the integrated rice-prawn system is a suitable alternative to make rice production economically feasible on small farms without government subsidies.