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A B S T R A C TEggs of 20 females were sampled to analyze lipid, protein, and carbohydrate content during the embryonic development of Cherax quadricarinatus. Sampling was performed on recently spawned eggs to first juvenile stage. Ten eggs were sampled every 48 h during the first two weeks and every 72 h thereafter for biochemical analysis. Total proteins, lipids, and carbohydrates were measured. Proteins were the most abundant egg component (63.2%), followed by lipids (32.3%), and carbohydrates (4.4%). A steady decrease of lipid content was observed ( y 5 895.38 2 9.93x, r 2 5 0.94; y 5 lipid concentration, x 5 days). For proteins, two different depletion rates were observed, with the initial rate maintained for 30 days ( y 1 5 1,443.0 2 4.46x 1 , r 2 5 0.90) and an increased depletion rate after hatching ( y 2 5 1,936.60 2 21.10x 2 , r 2 5 0.96). Carbohydrates were always present as a minor constituent, and its concentration did not change significantly. Water content increased from 52% in recently spawned egg to 85% in juveniles. Energy equivalents were calculated from each component, and the overall energy expenditure is represented by the equation y 5 13.86 2 0.11x (r 2 5 0.95). Relevant morphological features for each sample day are indicated.

RESUMEN.Los langostinos del género Macrobrachium con interés económico y pesquero son bien conocidos y explotados en casi todas las comunidades ribereñas de Latinoamérica. Sin embargo no han sido estudiados apropiadamente, y su conservación está en riesgo. Las características económicas, sociales y culturales, de la mayoría de los países de la región, que se traducen en el deterioro del hábitat y la sobreexplotación pesquera, ponen en peligro de desaparición las poblaciones de este género de macroinvertebrados acuáticos. De esto, se desprende que todas estas especies están escasamente estudiadas y el estado actual de sus poblaciones no es conocido, si bien en el caso de M. amazonicum hay numerosos estudios. Las técnicas de cultivo es el rubro en que más investigación se ha realizado. En este trabajo se resume el conocimiento que se tiene sobre las especies nativas de Macrobrachium en Latinoamérica y se discute su importancia económica y necesidades de conservación.

We determined the effect of four concentrations of dietary crude protein, 30.7, 37.2, 41.8 and 46.8% on growth rate, survival and body composition of the juvenile cauque river prawn (Macrobrachium americanum). The prawns were hatched in the laboratory from the spawn of one wild ovigerous female. Prawns consuming 37.2% crude protein reached a final weight of 0.58 g (feed conversion ratio of 2.15), which was significantly better than the other treatments. Survival was 100% in all treatments. Protein content in the diets had no significant effect on whole body proximate composition and amino acid profile. Juveniles consuming the 37.2% crude protein diet grew faster than those fed the other diets. Specific growth rate was adjusted to the two-slope broken-line regression analysis model to estimate the optimal protein requirement. In conclusion, these results demonstrated that the 37.2% protein level diet is optimal for juvenile cauque river prawn M. americanum in the experimental conditions of this study.

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