Effect of Different Feeding Strategies on Production and Economic Returns for Freshwater Prawn, Macrobrachium rosenbergii, Raised in Earthen Ponds in a Temperate Climate

Abstract

This study compared the current recommended technology of “phase-feeding” diets, increasing in nutrient density as the relative prawn, Macrobrachium rosenbergii, biomass increased, compared to feeding a steam-pelleted, practical diet containing 32% protein throughout the entire production period. Two treatments were evaluated. Treatment 1 was phase-feeding where prawn were fed unpelleted distillers grains with solubles (DDGS) for the first four weeks; fed a steam-pelleted prawn diet containing 28% protein for weeks 5-12; and fed an extruded marine shrimp diet containing 40% protein for weeks 13-18. In Treatment 2, prawn were fed a 28%-protein, steam-pelleted diet throughout the entire 18-week production period. Feeding rates in both treatments were based on a feeding table. There were three replicate 0.02-ha ponds for each treatment. All ponds were stocked at 87,500/ha and were provided with artificial substrate in the form of polyethylene “safety fence” oriented vertically at a rate to increase available surface area 50%. After 97 culture days, there was no significant difference (P > 0.05) between treatments in terms of production, average individual weight, FCR, or survival which averaged 2,272 kg/ha, 28.4 g, 2.2, and 92%, overall. However, the percentage of prawns which reached over 30 g was increased approximately 20% in the phase-fed treatment. The added expense of the marine shrimp diet resulted in approximately a US $1.00/kg increase in the break-even price in the phase-treatment compared to feeding the diet containing 28% protein exclusively. There appears to be little benefit to feeding expensive marine shrimp diets to freshwater prawn; however, if the market being addressed requires, or pays, more for large animals, some added expense may be justified.