Nutritional Depletion of the Aquaculture Feed Organisms Euterpina acutifrons, Artemia sp. and Brachionus plicatilis During Starvation

The nutritional quality of the harpacticoid copepod Euterpina acutifrons , freshly-hatched Artemita nauplii, juvenile and adult Artemia , and the rotifer Brachionus plictatilis , in fed and starved conditions, was evaluated through the use of ratios of dry weight to wet weight (DW/WW), ash-free dry weight to dry weight (AFDW/DW), calories per mg ash-free dry weight (cal/mg AFDW), and carbon to nitrogen by weight (C/N). E. acutifrons had in nearly all cases the highest values of DW/WW, AFDW/DW, and cal/mg AFDW. Calculated losses in caloric content per unit of wet weight (cal/mg WW) during one day's starvation were similar among species, ranging from 3 to 52 percent. C/N ratios were less variable, but also reflected starvation-related changes indicating depletion of C relative to N, which is consistent With depletion of lipids and carbohydrates relative to protein.
Because little or no change in caloric density of organic material (cal/mg AFDW) was observed in any species under either condition, decreases in caloric content of wet weight or of individuals were due to decreases in DW/WW and AFDW/DW. Caloric content and carbon content were related by the factor 11.3 cal/mg C. Starvation-related losses in the nutritional value of forage organisms can be important in larval rearing systems.