Different applications of Arthrospira platensis microalgae in the production of Pacific white shrimp Litopenaeus vannamei
Author: Joaquin Macias Sancho (Currículo Lattes)
Supervisor: Dr Luis Henrique da Silva Poersch
Co-supervisor: Dr Marcelo Borges Tesser
Abstract
The present thesis aimed to evaluate different methods of inclusion of the microalgae Arthrospira platensis in the cultivation of the Pacific white shrimp Litopenaeus vannamei during the nursery and fattening phases and its effects on the quality of the culture water, on performance, survival, immune system and on shrimp microbiota. The first chapter aimed to apply the powdered and live cyanobacterium A. platensis in the biofloc production system to enrich microbial aggregates and evaluate the effects on water quality and shrimp survival. The inclusion of microalgae in live form influenced the water quality of the culture medium, increasing the values of ionized ammonia in the system. However,this detriment in the water did not cause effects on the survival of the shrimp, obtaining higher survival values in the treatments where the cyanobacteria was placed than in the control treatment due to its immunostimulating effect. The inclusion of microalgae A. platensis in the production systems of post-larvae of white shrimp is recommended to achieve better survival rates. In the second chapter, we worked on the possibility of co-producing A. platensis in a super intensive system of clear water for juvenile white shrimp and the evaluation of the effects of cyanobacteria on performance, survival, immune system and water quality. During the experimental phase of the treatment where it was inoculated, A. platensis reached ammonia levels above those recommended for the production of the species,but the shrimp growth data was higher for this treatment. There was also an improvement in immunological parameters when cyanobacteria was inoculated. Microalgae co-production was not possible due to the high density of shrimp cultivation used, but A. platensis demonstrated positive effects on the growth and on the immune system of L. vannamei. The third chapter evaluated different levels of substitution of fish meal for flour of A. platensis (0%, 5.0%, 10%, 25%, 50%, and 75%) and the function as a prebiotic of cyanobacteria. White shrimp juveniles were fed for 49 days and through histological analysis of the shrimp intestine differences were found in the deposition of Gram positive bacteria,maintaining a positive linear relationship in the presence of this type of bacteria with the increase in the level of substitution of fish meal for cyanobacterial flour. The fourth chapter of the thesis aimed to evaluate the effects of six diets with levels of substitution of 0%, 5%, 10%, 25%, 50% and 75% of fish meal for A. platensis meal on performance, composition proximal, color, carotenoid content, immune system and antioxidant status in juveniles of L. vannamei. High levels of A. platensis substitution caused higher growth rates, increased protein deposition in the muscle, more reddish colorations in cooked prawns, higher concentrations of carotenoids in the muscle, decreased apotheosis rate and differences in antioxidant status.The results obtained in the present study evaluate the capacity of microalgae A. platensis as an alternative ingredient for shrimp diets, contributing to the improvement of the immune system and survival in a super intensive production system of post-larvae and juvenile Pacific white shrimp, and the positive effects such as prebiotic, on performance, color, immune system and antioxidant status of juvenile shrimp in intensive production systems in clear water. The use of microalga A. platensis as an alternative ingredient to fishmeal will not influence the performance of the prawns, it will incorporate positive effects on their health and will reduce the use of fishmeal in the formulation of feeds for L. vannamei.