Different protein levels in a super-intensive culture of juvenile Pacific white shrimp (Litopenaeus vannamei) in biofloc systems during the early rearing phase

Abstract

The determination of crude protein levels in diets of aquatic organisms allows maximizing growth, decreasing feed costs, and improving water quality. A rearing culture of Litopenaeus vannamei was carried out in superintensive biofloc systems using five diets with different crude protein (CP) levels (320 g·kg-1 CP, 360 g·kg-1 CP, 400 g·kg-1 CP, 440 g·kg-1 CP, and 480 g·kg-1 CP); each diet was used in quadruplicates. The experimental period lasted 35 days, and the shrimps (0.59 ± 0.001 g) were stocked at the density of 600 PL·m-3, using 20 experimental units (50 L of useful volume). There were no significant differences in animal survival between treatments (p > 0.05). The animals fed with 480 g·kg-1 presented higher final weight and specific growth rate when compared to the treatments fed with 320 g·kg-1 (p < 0.05). Furthermore, feeding shrimp with 32% CP diets results in a reduction in feed utilization and nutrient retention, thus increasing feed costs. Overall, according to the broken line analysis, 38% CP would be ideal, and according to the quadratic regression 46% CP would result in the best growth of L. vannamei at this growth stage.