Tropentag, October 6 - 8, 2009 in Hamburg "Biophysical and Socio-economic Frame Conditions for the Sustainable Management of Natural Resources"

Evaluation of Protein-rich Feed Ingredients for the Organic Production of Freshwater Prawns Macrobrachium rosenbergii by Smallholders in the Inlands of Costa Rica

¹University of Hohenheim, Department of Animal Production in the Tropics and Subtropics, Germany
²University of Costa Rica, Escuela de Biología, Costa Rica

Abstract

In Costa Rica are many freshwater bodies unused for aquaculture purposes so far, although they are particularly suitable for the cultivation of freshwater prawn Macrobrachium rosenbergii. Such cultivation would be a possibility for raising the income of smallholders especially in case of ecologically produced prawns that are high-value-products. The aim of this study was to remove the lack of appropriate feeds by testing and comparing regional feed components for semi-intensive production of freshwater prawns considering the ecological background.
We evaluated two different test diets with a total maximum amount of 20% fish meal according to the guidelines of "Naturland" (Verband für ökologischen Landbau) as a potential certifier. The used fish meals and additional shrimp head meal were regional by-catches and processing wastes. Diet 1 contained 15% fish meal (Physiculus talarae) and 10% shrimp head meal (Heterocarpus vicarius) and diet 2 contained 20% fish meal (15% Pontinus cf sierra and 5% Hippoglossina bollmani) and 5% shrimp head meal (Heterocarpus vicarius). Further ingredients were integral wheat meal, sunflower oil, vitamins/minerals and gelatin. The test diets were compared to (1) a control feed used for the cultivation of marine shrimp (Nicovita) and to (2) a pellet feed for horses used in the only existing prawn farm in Costa Rica. A grow-out experiment was designed to determine the effect of the diets on growth performance and feed utilisation parameters of Macrobrachium rosenbergii. We used a randomised set-up of three natural ponds, each with four net cages of 2 m² for 28 days. The monitoring of the water quality parameters dissolved oxygen and water temperature showed no significant difference between the ponds. The highest weight gain (5.7 g ± 3.8) was achieved by diet 2 followed by the control feed Nicovita (4.4 g ± 2.8) and diet 1 (4.0 g ± 1.9). The lowest weight gain was observed by the pellet feed for horses (0.6 g ± 0.5).
These results indicate that the test diets used in this study are suitable feeds for Macrobrachium rosenbergii. Further research is needed to evaluate these feeds in different life stages of prawns and to optimise processing.

Keywords: Costa Rica, feed ingredients, Macrobrachium rosenbergii, organic production

Contact Address: Ulfert Focken, University of Hohenheim, Department of Animal Production in the Tropics and Subtropics, Fruwirthstraße 12, 70599 Stuttgart, Germany, e-mail: fockenuni-hohenheim.de