Comparison on the Effects of Earthworm- Formulated and Commercial Feeds on the Growth and Development of the Freshwater Prawn Macrobrachium rosenbergii (de Man)

Abstract

The aquaculture of prawns has been extensively practiced in Asia and throughout the world as a source of food and livelihood. This expanding industry led to the continuing pursuit of finding means of producing feeds at a cheaper price without compromising nutritional value. This study aims to compare the effects of the earthworm-formulated feeds and commercial feeds with respect to the growth and development, survival and behavior of Macrobrachium rosenbergii (de Man) prawns. Two set-ups containing 30 two-month old juvenile prawns were fed with commercial and earthworm-formulated feeds. The body length, body width, weight, survival rate and behavior of the prawns were observed for four weeks. A paired sample T-test showed no significant difference among the morphometric variables and survival of M. rosenbergii fed with earthworm-formulated and commercial feeds during tire experiment. Feeding behaviour was not clearly observed since prawns tend to leave the food out in the water for a long time before approaching. Feeding duration took several hours and only roughly half of the feeds were consumed. No aggressive behavior was observed among the prawns however clinging on the screen was common among them. Survival rate is higher during the first two weeks in the commercial feeds (CF) group which later showed similar results with the earthworm-formulated (FF) group as prawns decline in number for both set-ups in the succeeding weeks. A test for calcium was conducted between the feeds and was found that calc ium was absent for both. It was speculated that mortality was a result of the lack of calcium in both the feeds and the set-up and that laboratory conditions are not ideal in the culture of prawns. The FF group showed comparable results with the CF group in terms of the body length, width, weight and survivability; therefore, earthworm-formulated feeds can be used in place of the commercial feeds provided that nutrients not found in the formulation be supplemented in the diet. Furthermore, a field experiment must be conducted for a more conclusive result.