Dietary inclusion of microalgae meal for Pacific white shrimp ( Litopenaeus vannamei): Effects on growth performance, flesh quality, and immunity

Microalgae have emerged as a promising supplement or feed additive and ensure sustainability standards in aquaculture. The present study aimed to investigate the effects of dietary marine microalgae, Phaeodactylum tricornutum and Tetraselmis sp., supplementation on growth performance, feed intake, tissue morphology, biochemical characteristics of some tissues and expression of immune related genes in hepatopancreas of Pacific white shrimp, Litopenaeus vannamei. L. vannamei (about 0.8 g) was fed six isonitrogenous and isolipidic diets including six dietary marine microalgae (P. tricornutum: Tetraselmis sp. = 1: 1) content 0 (CON), 1.5 % (MA-1.5 %), 3 % (MA3 %), 4.5 % (MA-4.5 %), 6 % (MA-6 %) and 7.5 % (MA-7.5 %) for 9 weeks. Subsequently, the shrimp was challenged with Vibrio parahaemolyticus injection. Microalgae supplementation could increase the survival rate of from 78.33 % to 100 % and decrease the feed conversion ratio from 1.66 to 1.37. Additionally, microalgae significantly decreased the crude lipid and increased the content of n-3 PUFA in the muscle (P > 0.05). The intestinal villi in MA-4.5 % had the greatest height and maintained the most intact shape. Following 8 h of V. parahaemolyticus stress, the mortality rate of shrimp in MA-3 % group was 1/6 that in CON group. Furthermore, the MDA content in hepatopancreas was significantly lower in the MA-3 % group compared to the CON group (P > 0.05). Gene expression analysis revealed significant upregulation of antibacteriarelated genes (alf1, alf2, crus, lyz, pen3a and pen4), proPO system-related genes (sp, pexn, propo1 and propo2), and antioxidant gene cat in the hepatopancreas of shrimp from the MA-3 % group (P > 0.05). In conclusion, the findings from this study indicate that the microalgal mixture is an effective dietary additive for L. vannamei, promoting improved growth performance, enhanced flesh quality, and stronger immunity.