INFLUENCE OF DIETARY PROTEIN CONCENTRATION ON GROWTH, FEED CONVERSION AND GENERAL METABOLISM OF JUVENILE PRAWN (Macrobrachium rosenbergii)1

ABSTRACT Juvenile Macrobrachium rosenbergii cultured in closed systems were offered one of four dietary protein concentrations, each containing a 1.65:1 ratio of menhaden fish meal to soy proteinate. After 6 and 10 weeks, the 40 and 49% protein treatments promoted significantly higher weight gain than those individuals offered 32 and 23% protein. Additionally, during the same time intervals, the 32% protein treatment resulted in better growth of prawn than the 23% protein treatment. After 14 weeks, prawn fed the 40% protein concentration produced a significantly higher cumulative weight gain than prawn offered 49, 32 and 23% protein. Feed conversion ratios were significantly lower (i.e., better) in the 40% protein treatment compared to the 23% protein treatment after 10 and 14 weeks (P ≤ 0.05). Survival rates were similar for all dietary treatments within any one time interval (6, 10 and 14 weeks). Protein efficiency ratio was lower in prawn fed 49% protein vs 40% proten after 10 weeks. The 40% protein treatment was more cost‐effective than 49% protein treatment throughout the study when considering growth, feed conversion ratios and protein efficiency ratios. Although these results indicate a higher total dietary protein requirement for this species than that reported for most other prawns (27–35% protein), exact requirements will undoubtedly vary with alterations of the amino acid profile, variation in dietary supplementation of macro‐and micronutrients other than protein, and changes in selected environmental factors.