Maintaining shrimp performance under environmental stressors remains a key challenge for aquaculture. Yeast cell wall (YCW) fractions derived from brewer’s yeast (Saccharomyces cerevisiae) are increasingly investigated as dietary additives to enhance resilience. This study examined the effects of YCW supplementation (Biolex® MB40, Leiber GmbH) on growth performance and intestinal microbial communities of whiteleg shrimp (Litopenaeus vannamei) reared under suboptimal temperature (22 °C).
Juvenile shrimp (3.0 ± 0.1 g) were reared for 35 days in a semi-recirculating aquaculture system (salinity 30 ppt; 14% daily water exchange) and fed one of three isoproteic and isolipidic diets: a control diet (0-YCW), or diets supplemented with 0.1% (0.1-YCW) or 0.2% YCW. Each treatment was tested in four replicate tanks (10 shrimp per 30-L tank), with shrimp fed ~3.5% body weight per day.
At the end of the trial, survival ranged between 88–90% and did not differ significantly among treatments. Shrimp fed the 0.1-YCW diet attained the highest weight gain, which was significantly greater than that of the 0.2-YCW group (P = 0.025) but not different from the control. Specific growth rate showed a trend towards improvement in the 0.1-YCW group (P = 0.054), while feed conversion ratio and protein efficiency ratio were unaffected.
Preliminary intestinal microbiome analyses revealed treatment-associated shifts in community composition. Beta diversity differed significantly between groups (PERMANOVA, P < 0.01), alpha diversity varied by sampling timepoint, and random forest classification achieved high accuracy (AUC ≈ 0.97) in distinguishing treatments. The intestinal microbiota of shrimp across dietary treatments was dominated by the genera Cetobacterium, Burkholderia-Caballeronia-Paraburkholderia, and Aeromonas.
Overall, these findings indicate that 0.1% YCW supplementation supported higher growth than 0.2% YCW but did not significantly outperform the control diet. Microbiome analyses suggest dietary YCW influences intestinal community structure, which, alongside forthcoming histological, immunological, and gene expression analyses, will provide further insight into its potential role in enhancing shrimp resilience under prolonged suboptimal temperature.