The objective of this study was to evaluate the effect of salinity on the culture water quality, performance and body composition of Litopenaeus vannamei juveniles (1.16±0.30 g) reared for 36 days in a super-intensive system without water exchange at salinities of 4, 16 and 32‰. Groups of 200 animals (140/m2) were stocked, with three replicates, in nine fiber-cement tanks (1.11 × 1.29 × 0.70 m) with a useful volume of 400 L. Physical and chemical parameters of water, such as temperature and dissolved oxygen before and after midday, pH, alkalinity, total suspended solids, total ammonium nitrogen, nitrite, nitrate, and phosphate, were monitored. Performance parameters like survival, weight gain, specific growth rate, feed conversion ratio and protein retention rate, were also evaluated. The proximate composition of the juveniles was analyzed through the moisture, protein, lipid and ash contents. The physical and chemical parameters of the water were influenced by the treatments. The increased salinity produced a significant increase in the alkalinity and the concentrations of total suspended solids, nitrite and phosphate. Of the parameters that were examined to evaluate the performance and proximate composition of the shrimp, only survival, protein retention rate and body lipid content were significantly influenced. The highest values were found at a salinity of 32‰. However, the analysis of the proximate composition of the bioflocs showed that the moisture, protein and lipid contents increased as the salinity decreased. Growth, use of feed and survival of L. vannameijuveniles reared in a super-intensive system without water exchange is positively influenced by an increase of salinity from 4 to 32‰.

Este estudo foi realizado com o objetivo de avaliar a possibilidade de reduzir a concentração proteica da dieta para pós-larvas de camarão-branco-do-pacífico (Litopenaeus vannamei) por meio da suplementação do aminoácido taurina. Seis dietas práticas, isoenergéticas (15,48 kJ EM/g), foram formuladas para conter duas concentrações de proteína (35% e 45% proteína bruta, PB), com três níveis de suplementação de taurina (0, 5 e 10 g/kg), em arranjo fatorial 2 × 3, com quatro repetições. Cem pós-larvas (peso inicial de 0,14 ± 0,01 g) foram estocadas em cada um dos 24 tanques de 45 litros conectados a um sistema de recirculação de água marinha. As dietas experimentais foram distribuídas aos camarões (10% da biomassa) três vezes ao dia, durante 30 dias. A concentração proteica da dieta não influenciou o crescimento nem a utilização alimentar das pós-larvas, mas o efeito benéfico da suplementação das dietas com taurina foi evidente em ambos os níveis proteicos testados. As pós-larvas alimentadas com as dietas com maior concentração de taurina (10 g/kg) alcançaram maior peso final, ganho em peso e taxa de crescimento específico e melhor conversão alimentar em comparação àquelas alimentadas com as demais dietas. A taxa de sobrevivência média foi superior a 92% e não foi afetada pelas dietas experimentais. O nível de 35% de PB na dieta (22,58 mg PB/kJ EM) é suficiente para promover o crescimento adequado de pós-larvas de L. vannamei, e o desempenho dos camarões pode ser melhorado com a suplementação de 10 g taurina/kg de ração.

The present study aimed to evaluate the possibility of reducing the dietary protein content for post-larvae of Pacific white shrimp (Litopenaeus vannamei) through diet supplementation with taurine amino acid. Six practical isoenergetic (15.48 kJ ME/g) diets were formulated to contain two protein concentrations (35% and 45% crude protein, CP) and 3 levels of taurine supplementation (0, 5 and 10 g/kg) in a 2 × 3 factorial scheme, with four replicates. One hundred post-larvae (initial weight 0.14 ± 0.01 g) were stocked in each of twenty-four 45-L tanks, connected with recirculating marine water system. Shrimps were fed the experimental diets (10% biomass) 3 times a day for 30 days. Dietary protein concentration did not influence growth neither feed utilization of the post-larvae, but a benefic effect of the diet supplementation with taurine on both protein levels tested was evident. Post-larvae fed diets with the highest taurine supplementation (10 g/kg) achieved significant higher final weight, weight gain, specific growth rate and better feed conversion than those fed the other diets. Average survival rate was greater than 92% and it was not affected by experimental diets. Crude protein level of 35% in the diet (22.58 mg CP/kJ ME) is enough to promote adequate growth of L. vannamei post-larvae and shrimp performance can be improved with supplementation of 10 g taurine/kg of ration.