Graded inclusion of yellow mealworm (Tenebrio molitor) larvae meal alters egg nutritional composition, antioxidant capacity, and sensory profile in laying hens

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This study evaluated the effects of graded dietary supplementation with yellow mealworm ( Tenebrio molitor , TM) larvae meal on laying performance, egg quality characteristics, and cecal microbiota in laying hens. A total of 360 Hy-Line White hens (34 weeks old; 1.54 ± 0.08 kg) were assigned to five dietary treatments (0 [CON], 2% [TM2], 4% [TM4], 6% [TM6], and 8% TM larvae meal [TM8]) for 70 d, with six replicates per treatment and 12 hens per replicate. Supplementation with TM larvae meal did not affect laying rate or feed conversion ratio ( P > 0.05). In terms of egg nutritional composition, diets containing 4%-8% TM larvae meal significantly increased total amino acid and essential amino acid contents compared with the CON ( P < 0.05), with significant increases in tyrosine, valine, cystine, aspartic acid, and glutamic acid (except for TM4 group) contents ( P < 0.05). While total polyunsaturated fatty acids (PUFA) content remained unchanged ( P > 0.05), supplemental TM larvae meal in diets increased the contents of saturated fatty acids and monounsaturated fatty acids in both linear and quadratic fashions ( P < 0.05). The ω-6/ω-3 PUFA ratio also increased linearly ( P = 0.003) and quadratically ( P = 0.015). However, the 4% TM larvae meal diet maintained a ratio comparable to the CON ( P > 0.05); whereas higher inclusion levels significantly elevated this ratio ( P = 0.027). Electronic nose analysis revealed dose-dependent reductions in off-odor compounds ( P < 0.05), while texture analysis showed increased yolk chewiness and cohesiveness in the TM4, TM6, and TM8 groups compared with the CON group ( P < 0.05). Dietary TM larvae meal supplementation also enhanced antioxidant capacity, as reflected by increased serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities and reduced egg malondialdehyde (MDA) levels in the TM4, TM6, and TM8 groups when compared with CON ( P < 0.05). Cecal microbiota profiling indicated dose-dependent enrichment of specific genera, including Butyricimonas ( P = 0.013). Correlation analysis showed that the relative abundance of Colidextribacter and Butyricimonas were positively associated with serum antioxidant indices and negatively correlated with egg MDA levels ( P < 0.05). In conclusion, a 4% TM larvae meal inclusion level enhances egg amino acid profiles, sensory traits, and antioxidant capacity without compromising performance or the yolk ω-6/ω-3 PUFA ratio.