Gut Loading of Yellow Mealworm (Tenebrio molitor) Larvae with Dried Carrot: Effects on Retinol, Carotenoids, Tocopherols, Fatty Acid Profile, and Oxidative Status Biomarkers

Gut loading may improve the nutritional value of feeder insects used for insectivorous animals. This study evaluated the effects of dried carrot inclusion in wheat-bran-based diets on the chemical composition, lipid-soluble bioactive compounds, fatty acid profile, and oxidative status of yellow mealworm (Tenebrio molitor) larvae. Larvae were assigned to three dietary treatments (10 replicates per treatment) and fed for 48 h with wheat bran alone (WB), 50% dried carrot and 50% wheat bran (DC50), or 75% dried carrot and 25% wheat bran (DC75). Dried carrot inclusion did not affect the proximate composition of the larvae. Retinol concentration was higher in DC75, whereas β-carotene, lutein, and zeaxanthin increased with increasing dried carrot inclusion. In contrast, α-, β-, and total tocopherol concentrations were lower in carrot-fed larvae. Dried carrot also modified the fatty acid profile, affecting several individual fatty acids as well as total polyunsaturated fatty acids (PUFA) and the n-6/n-3 PUFA ratio. Peroxidase and superoxide dismutase activities were unaffected, whereas malondialdehyde concentration was lower in DC75 than in WB. These results indicate that short-term feeding with dried carrot increases carotenoid concentrations in whole mealworm larvae and modifies selected indicators of lipid quality and oxidative status.