Introduction
Hepatopancreatic microsporidiosis (HPM), caused by Enterocytozoon hepatopenaei (EHP), is an major constraint in shrimp aquaculture, leading to growth retardation and reduced performance. As no effective pharmaceutical treatment is currently available, nutritional strategies to support resilience are of interest. This study evaluated krill meal (KM) as a functional dietary ingredient to mitigate the impact of EHP infection in Pacific white shrimp (Penaeus vannamei).
Materials and Methods
A controlled tank trial was conducted using juvenile shrimp (4–5 g) fed diets containing 3%, 6%, and 9% KM for eight weeks, alongside infected and non-infected control groups. In an additional challenge setup, shrimp were pre-fed either a control diet or a 6% KM diet for 25 days prior to EHP exposure via ingestion of infected hepatopancreatic tissue. Growth performance, feed conversion ratio (FCR), survival, hepatopancreatic histology, pathogen load (qPCR), and proteomic responses were evaluated.
Results and Discussion
KM inclusion significantly improved growth, FCR, and survival compared to control groups (p<0.001), with the strongest responses observed at 6% and 9% inclusion levels. Histological analysis showed a higher abundance of R cells in KM-fed shrimp, indicating improved hepatopancreatic functional capacity (p<0.001).
Quantitative PCR analysis demonstrated a reduction in EHP copy number in KM-fed groups (p<0.001), suggesting improved ability to cope with infection. Proteomic profiling indicated modulation of immune-related and stress-response proteins, consistent with enhanced physiological responses observed in performance outcomes.
Conclusion
Krill meal acts as a functional nutritional strategy to support shrimp performance and hepatopancreatic condition under EHP challenge. KM inclusion in diets contributes to improved growth, survival, and reduced pathogen load, supporting a nutritional approach to managing EHP in shrimp production systems.