Nine dietary combinations of crude protein (37, 47, or 57%) and lipid (7, 12, or 17%) concentrations were evaluated for their effects on growth, feed efficiency, protein‐efficiency ratio, protein retained, and whole‐body composition of age‐0 striped bass Morone saxatilis (initial mean weight, 1.4 g) over 10 weeks. Increasing dietary protein concentration generally improved weight gain of striped bass. Striped bass fed diets containing 37% crude protein plus 7% lipid had lower weight gain than fish fed 47% crude protein plus 12% lipid or 57% crude protein plus 17% lipid. Whole‐body protein concentrations increased with higher dietary protein concentrations and lower dietary lipid concentrations. Highest whole‐body protein concentration occurred in fish fed 57% crude protein plus 7% lipid. Lowest whole‐body protein concentration occurred in fish fed 37% crude protein plus 17% lipid. Whole‐body lipid concentrations increased with higher dietary lipid concentrations and lower dietary protein concentrations. Highest whole‐body lipid concentration occurred in fish fed 37% protein plus 17% lipid. Lowest whole‐body lipid concentration occurred in fish fed 57% crude protein plus 7% lipid. Feed efficiency, protein‐efficiency ratio, and protein retained increased as dietary lipid concentration increased. Feed efficiency also increased as dietary protein increased.

Age-0 striped bass Motone saxatilis were fed one of three formulated diets containing 34%, 44%, or 55% crude protein or a blueback herring Alosa aestivalis reference diet. Striped bass fed the 55% crude-protein formula diet had the highest average weight gain and feed efficiency. Protein efficiency ratio and protein retained were highest in striped bass fed the 34% crude protein diet. Whole-body protein concentration was unaffected by dietary protein concentration. Whole-body moisture increased, and whole-body lipid decreased, with increasing dietary protein concentration. Striped bass whole-body lipid concentration was negatively correlated with wholebody moisture concentration within each dietary treatment. References

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.

Cellulose fiber comprising up to 30% of an isonitrogenous series of diets (0, 5, 15 and 30% fiber concentration) did not suppress growth of prawn having average initial weights of 0.08 ± 0.002 g over a 12‐week period. In addition, dietary fiber concentrations of 5 and 20% were found to stimulate growth over an 8‐week period among prawn having initial average weights of 1.48 ± 0.054 g, as opposed to 0% fiber concentration, which had no significant effect on growth. Cellulase activity measured in hepatopancreas tissues by viscometric techniques was shown to be positive with a six‐fold increase in activity occurring in adult prawn (11 ± 1.16 g) when compared to smaller prawn (1 ± 0.06 g). However, activity in both sizes of prawn was not found to be proportional to increases in dietary fiber concentrations. Total organic carbon assimilation decreased while nitrogen assimilation efficiency increased in response to increasing dietary fiber concentration. Results from the present study indicated that use of dietary fiber may make a significant contribution to commercial formulations of cost‐effective crustacean diets.

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