The use of Dextrose as a carbon source in the development of bio-flocs and performance of the white shrimp (Litopenaeus vannamei) grown in a system without water renewal
Author: Sabrina Medeiros Suita (Currículo Lattes)
Supervisor: Dr Wilson Francisco Britto Wasielesky Junior
Co-supervisor: Dr Paulo Cesar Oliveira Vergne de Abreu
Abstract
The objective of this work was to evaluate the effect of dextrose as a carbon source in the development of bio-flocs, in addition to its contribution to the maintenance of water quality and to the performance of juvenile white shrimp (Litopenaeus vannamei) grown in super-systems. intensive without water renewal. Two treatments, Dextrose and Molasses, were used with four repetitions each. The carbon addition was performed maintaining a C: N ratio of 20: 1 and CN-AT of 6: 1. The physical and chemical parameters of water such as temperature, pH, salinity, dissolved oxygen and transparency (Secchi) were monitored daily. Shrimp growth was monitored using periodic biometrics.At the end of the experiment, the shrimp remaining in each tank were counted to determine the survival rate and the biomass produced in each treatment. The feed conversion rate was calculated from weight gain and the amount of feed consumed by the shrimp. During the experiment, samples were collected every three days to evaluate dissolved organic carbon, chlorophyll-a, suspended solids, flake volume and ammonia, nitrite, nitrate and phosphate concentrations. The composition of microorganisms present in water and microbial flocs were quantified and classified by groups. The water quality parameters remained within an acceptable range for the cultivation of this species. The transparency of the crop water appears to have influenced the performance of the microbial community.It can be seen that both treatments had the same performance in controlling ammonia, although the formation of bio-flocs occurred earlier in the treatment of molasses. Although there were differences in the formation of bio-flocs in the first two experimental weeks, a better performance of the shrimp in the treatment with the use of dextrose can be noted, however, the high levels of nitrite may have caused low survival rates and final average weight. in both treatments. From the data obtained in the present study, it can be suggested that the use of dextrose as a carbon source may provide better zootechnical indices for the cultivation of Litopenaeus vannamei in super-intensive systems without water renewal