Three extruded diets were formulated and used to cultivate Macrobrachium rosenbergii prawns. For ninety days, the prawns were fed on the similarly balanced isonitrogeneous and isoenergetic diets, based on albumin and linseed (Linseed diet), on whey proteins concentrate (WPC) and soybean oil (Whey proteins diet), and on albumin and soybean oil (Control diet). Every thirty days, the shrimps were weighed and submitted to analyses. The results showed that the average body weights for the shrimps fed on the Linseed and Whey proteins diets were approximately sixty percent higher than for those fed on the Control diet. No significant differences were found for the protein content and the total lipid content in shrimps fed on the diets. However, the Linseed diet led to the lowest cholesterol level and improved the ratio between the sum of n-6 and the sum of n-3 fatty acids in the whole body of shrimps. WPC was used for the first time as a protein source for shrimp feeds, and may be considered as a component to be used in extruded diets for aquaculture. The results suggested that the experimental diets succeeded to provide shrimps with greater weight gain and nutritional value.