Influence of Limnospira platensis Extract on Zootechnical and Immune Parameters of Penaeus vannamei.

This study evaluated the immunomodulatory and histological effects of dietary supplementation with an ethanol extract of Limnospira platensis (spirulina) in Penaeus vannamei. Shrimp were fed diets supplemented with 0.5%, 1%, 2%, and 4% spirulina extract for 35 days. Growth performance did not differ significantly among treatments, suggesting no adverse effects on nutrient utilization. However, immune parameters, including granulocyte abundance and hemocyte phagocytic capacity, improved significantly at 0.5-2% inclusion levels, with 0.5% promoting the highest granulocyte counts and 2% maximizing phagocytic activity. In contrast, the 4% treatment led to a decline in both granulocyte levels and phagocytosis, indicating saturation effects at higher doses. Histological analyses supported these findings, as villus length improved with 0.5, 1 and 2% doses but not with 4%. Overall, these results confirm a non-linear immunostimulatory response of L. platensis extract, highlighting low inclusion levels, especially 0.5%, as effective and economically feasible strategies to strengthen shrimp immunity in intensive aquaculture.