| Resumo: |
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‰.
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