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Evaluation of three diets with different protein content in the culture of river prawn postlarvae, Macrobrachium rosenbergii

Abstract:

We evaluated the growth and survival of M. rosenbergii postlarvae fed with two commercial diets currently used for culturing freshwater fishes (P-28 and P-25) and a diet formulated for marine shrimp culture (P35), having different protein levels. The experiment lasted 30 days carrying out sampling of the animals after 15 and 30 days of culture. The postlarvae were cultured in 3.2 L aquaria at a density of 50 organisms per aquaria, using four replicates and one aquarium for replacements, for each diet. The diets were administered twice a day at a rate of about 10% of wet body mass of the animals. The relationship length/weight of the animals with the different diets were significant with a high correlation coefficient (r>0.90) and followed a linear model. They showed an alometric growth, and non significant differences among their slopes. Other growth parameters did show statistically significant differences among the diets, especially at 15 days of culture. At this time, P-25 showed highest total length and relative weight gain. The RNA/DNA index at day 30 was highest for P-25, and P-35 was intermediate. At this time, food conversion ratio for P-25 (1.57) was about 27% lower than the other two diets. These results, along with the biochemical analysis of the evaluated diets, suggest the use of diets with 25% protein content and high carbohydrate content for culture of M. rosenbergii postlarvae. It is proposed to study the use of diets with protein content lower than 25% to determine the possibility to lower the costs. © 2007 Instituto Nacional de Investigaciones Agricolas INIA.