Gross energy levels in practical diets for the Amazon river prawn postlarvae, Macrobrachium amazonicum

The present study evaluated the effect of different energy levels (15.07, 15.91, 17.17, 18.00, and 19.68 kJ [g.sup.-1] of diet) on isoproteic practical diets for Macrobrachium amazonicum during the nursery phase on the zootechnical performance and proximate composition of the whole body. Postlarvae with a mean weight of 0.043 [+ or -] 0.01 g were stored in 25 experimental units, at 150 animals per [m.sup.2], in a completely randomized design with five treatments and five replicates. The post-larvae were evaluated at the end of the experimental period according to the pre-established performance parameters. The analysis of variance for regression ([alpha] = 0.05) allowed us to estimate that the maximum final weight was observed in the treatment with 16.74 kJ [g.sup.-1]. In contrast, the lowest apparent feed conversion was observed at the 16.43 kJ [g.sup.-1] level. The best values were found in 17.29 and 17.50 kJ [g.sup.-1], respectively, for the energy and protein retention rates. As the best fit of the equation was presented for the energy retention ratio ([R.sup.2] = 0.63), which approached the treatment of 17.17 kJ [g.sup.-1], this energy level is recommended in postlarvae diets.