Enriched zinc and selenium agri-food by-products: effects on growth performance of black soldier fly

Selenium (Se) is an essential element for both animals and humans. It is involved in the func-tioning of several enzyme systems and various biochemical reactions, particularly those that protect cells from damage. Zinc (Zn), meanwhile, improves immune function by enhancing the immune response, making animals more resistant to infections and diseases. Black soldier fly (BSFL) larvae are recognized for their capacity to bioaccumulate microelements and can be reared on a wide range of substrates. Furthermore, the incorporation of Se and/or Zn has the potential to result in the production of an enriched insect meal. This study investigated the ef-fects of incorporating Zn and/or Se into the rearing substrate of black soldier fly larvae (BSFL). Five different substrates were evaluated: (I) a control diet based on plant ingredients (Gaines-ville diet, CTR); (II) a substrate derived from okara and potato waste (OkPa); (III) OkPa-Zn, supplemented with 150 mg/kg of Zn; (IV) OkPa-Se, containing 0.3 mg/kg of Se; and (V) OkPa-Zn+Se, enriched with both 150 mg/kg of Zn and 0.3 mg/kg of Se. The larvae were reared in darkness at 26 °C with 60% relative humidity, and their growth performance was assessed. For each diet, 500 larvae were used, with five replicates per treatment. The mean weight of individ-ual larvae was not significantly affected by the type of substrate (P>0.05). However, by the end of the trial, the CTR group exhibited a significantly higher total biomass (P<0.05). Survival rates remained consistent across all treatments (P>0.05). These findings suggest that okara and potato-based substrates, with and without Zn and Se supplementation, are suitable for BSFL rearing. Further research is recommended to explore the larval composition, trace mineral as-similation, and reproductive outcomes in black soldier fly.