A Comparison of Two Feeding Technologies in Freshwater Prawns, Macrobrachium rosenbergii, Raised at High Biomass Densities in Temperate Ponds

ABSTRACT

Recent developments in prawn production technologies (i.e., added substrate, increased stocking densities, size grading, and increased feed rates) have increased production rates from 900-1,000 kg/ha to over 2,500 kg/ha. While prawn can receive substantial nutritional benefit from natural foods at the lower biomass densities, at higher production rates prawn are likely to be more dependent on prepared diets. To ensure that maximum production is being achieved by these new production technologies, production rates must not be nutritionally constrained. This study was conducted to compare the current recommended technology of phase feeding of different quality feedstuffs to prawns of different sizes with the feeding of a high-quality penaeid diet throughout the production season. Two treatments were evaluated: Treatment 1 was phase feeding (current technology-control) where prawns were fed unpelleted distillers' grains with solubles (DDGS) for the first four weeks, then a 28%-protein prawn diet for weeks 5-12, and finally a 40%-protein penaeid diet for weeks 13-16. In Treatment 2, prawn were fed the 40%-protein penaeid diet throughout the entire production period. Feeding rates in both treatments were based upon a feeding table. Three 0.04 ha ponds were used for each treatment. All ponds were stocked at 59,280 juveniles/ha and were provided with artificial substrate in the form of a polyethylene “safety fence” oriented vertically to increase available surface area by 50%. After 106 culture days, no significant differences (P >0.05) were observed between treatments in terms of yield, average individual weight, food conversion ratio (FCR), or survival, which averaged 2,575 kg/ha, 46 g, 2.3, and 94%, respectively, overall. Due to the higher cost of the penaeid diet (US$0.84/kg), feeding costs for the penaeid diet treatment (Treatment 2) were 38% higher than those for Treatment 1. No benefit to using higher protein diets during the first 12 weeks of prawn pond production was observed.

Key Words:

• Macrobrachium
• freshwater prawn
• feeding
• diets