Development of the hepatopancreas and quality analysis of post-larvae Pacific white shrimp Litopenaeus vannamei produced in a BFT system

The production of marine shrimp in biofloc systems has a low environmental impact; the shrimp benefit from the maintenance of water quality and possibly utilize the system's microbial community as a food resource, which also positively affects the synthesis of digestive enzymes produced by the hepatopancreas. The aim of this study was to determine the performance, the post-larvae quality indicators and the development of the hepatopancreas and tubules of post-larvae Pacific white shrimp Litopenaeus vannamei produced in a BFT system during the nursery stage. Two experiments were conducted: NI (PL1-PL15; 75 shrimps L-1) and NII (PL16-PL30; 50 shrimps L-1). Both experiments included a control treatment simulating a traditional nursery with water renewal and a biofloc treatment without water renewal but including organic fertilization with dextrose every time the ammonia nitrogen concentration exceeded 0.5 mg L-1. Daily water quality analyses were performed. The best performance and the final quality of the production were observed in the biofloc treatment of both experiments. The total area of the hepatopancreas was significantly different between treatments in experiment NI, while the thickness of the tubules was significantly different between treatments in experiment NII. In both experiments, the hepatopancreas tubules from the biofloc treatment showed increased thickness and an apparent greater amount of enzyme producing cells (B cells) than the control treatment. The results suggest that when compared to conventional production systems, the bioflocs system may provide better nutritional support, allowing for proper development of the hepatopancreas and better nutritional conditions, resulting in healthier post-larvae shrimp.