Yosu Candela-Maldonado

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.

Aquaculture effluents rich in phosphorus and nitrogen (P and N) can lead to eutrophication of aquatic ecosystems. These nutrients may contribute to harmful algal blooms, oxygen depletion, and deterioration of water quality, which poses a threat to aquatic biodiversity. In shrimp diets, environmental impacts from P and N nutrient leaching can be reduced by improving dietary P digestibility through the use of alternative ingredients. While fishmeal, with its high phosphorus content, has traditionally been a primary source, its declining use due to cost and limited availability necessitates the inclusion of inorganic P sources to meet shrimp nutritional requirements. Optimising these sources ensures adequate phosphorus availability while minimising nutrient waste. This study evaluated the effects of inorganic phosphate supplementation (monoammonium phosphate, MAP; monosodium phosphate, MSP; and sodium calcium phosphate, SCP-2%) in standard diets (35% CP) on nutrient digestibility, residue generation, and performance of Litopenaeus vannamei. Results showed that phosphorus digestibility exceeded 96% across all phosphate sources, with MSP achieving the highest values. Calcium digestibility was notably higher in diets containing monocalcium phosphate, such as SCP-2%, which demonstrated superior digestibility values. No significant differences were observed in nitrogen or phosphorus excretion; however, residue analysis revealed that SCP-2% diets generated the lowest nitrogenous waste relative to ingested nitrogen, whereas MAP diets produced the highest nitrogen residues, followed by the Control diet. For phosphorus residues, the Control diet showed the greatest proportion relative to ingested phosphorus, followed by MSP. Phosphate inclusion did not affect shrimp growth, survival, or body composition. However, phosphorus and calcium retention efficiencies were inversely proportional to their dietary content, underscoring the importance of optimising phosphate sources to enhance nutrient utilisation and minimise environmental impact.

The use of eco-organic ingredients as a source of protein in aquaculture diets needs important attention due to the growing demand for organic seafood products. The present study evaluated the effects of fish meal substitution by different organic ingredients on the growth, body composition, retention efficiency, enzyme activity, and nutrient digestibility of white shrimp Penaeus vannamei. The four dietary formulations tested were formulated with organic ingredients and the fish meal was replaced by the following organic protein meals: Iberian pig viscera meal (PIG), trout by-product meal (TRO), insect meal (FLY), and organic vegetable meal (WHT), in addition to a control diet (CON) that included 15% fish meal. A growth trial was carried out for 83 days, raising 1 g shrimp to commercial size (20 g). Shrimp were stocked at 167 shrimp/m³ (15 individuals per 90 L tank). The results showed that the growth obtained by shrimp fed with TRO (19.27 g) and PIG (19.35 g) were similar in weight gain to the control diet (20.76 g), while FLY (16.04 g) and WHT (16.73 g) meals resulted in a significant lower final weight. The FLY diet showed significantly lower protein digestibility (68.89%) compared to the CON, PIG, TRO, and WHT diets, and significantly higher trypsin activity (0.17 mU/g) compared to shrimp fed with the PIG, TRO, and WHT diets. Shrimp fed with WHT have a significantly lower body weight percentage of protein (19.69%) than shrimp fed with the WHT and TRO diets, and some significant differences in dietary aminoacidic levels affecting amino acid body composition. These results indicate that Iberian pig viscera and trout by-product meal can successfully replace fish meal in Pacific white shrimp aquaculture.