Evaluation of dietary Haematococcus pluvialis in pilot-scale farming of Litopenaeus vannamei: Effects on production performance, physiological health, bacterial communities, and eukaryotic plankton

The dried Haematococcus pluvialis (H. pluvialis) powder rich in astaxanthin is widely investigated as a promising feed additive or ingredient for improving growth, health, feed efficiency, and pigmentation of aquatic animals under the controlled laboratory conditions, whereas few studies have reported its practical application efficacy in shrimp aquaculture. Hence, this study aimed to evaluate the practical effects of supplementation of 3.0 g H. pluvialis kg⁻¹ diet (47.6 mg astaxanthin kg⁻¹ diet) on water quality, production performance, health status, amino acids profile, bacterial communities, and eukaryotic plankton in the pilot-scale farming of Litopenaeus vannamei. After 45-day feeding, supplemental dietary H. pluvialis significantly enhanced the harvested biomass, survival rate, feed conversion ratio, and yield of shrimp farming, with no significant impacts on water quality parameters. The hepatopancreas antioxidant capacity and muscle essential amino acids of shrimp were also improved with dietary H. pluvialis supplementation, especially the decreased malondialdehyde and the increased arginine with statistical significance. The addition of dietary H. pluvialis changed bacterial communities with the dramatical variations of dominant phyla including Proteobacteria, Bacteroidetes, Cyanobacteria, and Actinobacteria in rearing water, shrimp intestine, and faeces. Likewise, dietary H. pluvialis significantly affected eukaryotic plankton with the decreased microalgae Picochlorum (class Trebouxiophyceae) and the increased protozoon Euplotes (family Euplotidae) in rearing water. Moreover, correlation analysis suggested that the enhanced production performance was closely associated with the significant improvements in shrimp antioxidant status, muscle amino acid profile, and intestinal microflora composition with dietary H. pluvialis addition. This study may provide valuable information for further practical application of H. pluvialis in larger commercial-scale production of L. vannamei farming.