Xiaotong Zhao, Ting Meng, Zhidong Zhang, Liping Hu, Xun Xiang
Vegetable trimming pellets (TVP) provide a potential route for recovering plant biomass as poultry feed, but their dose-dependent effects across production and biological compartments remain unclear. We evaluated diets containing 0% (A), 3% (B), 6% (C), or 9% (D) TVP (80% lettuce and 20% cabbage trimmings) in 240 17-wk-old Hy-Line Grey hens (6 pens of 10 hens per diet) for 12 wk. Diets had similar calculated crude protein, while calculated metabolizable energy decreased from 2.854 to 2.659 Mcal/kg. We assessed production, egg quality, serum, intestine, cecal microbiota and metagenome, and plasma and egg metabolomes. Full-period feed conversion ratio increased from 2.74 in A to 2.88 in D (P = 0.026), and average daily feed intake differed (P = 0.001), while egg production, egg weight, and egg mass remained similar (P > 0.05). At wk 12, shell breaking strength was lower in D than in A to C (3.55 vs. 3.92 to 4.02 kgf/cm²; P = 0.030), and yolk color differed among diets (P = 0.007). Serum hormones, several biochemical indices, catalase, and malondialdehyde differed at wk 12 (P < 0.05; marker-specific n = 3 to 6). Cecal community composition differed (permutational multivariate analysis of variance: R² = 0.571, P = 0.0006; dispersion P = 0.229), while Shannon diversity remained similar (P = 0.582). Five A-vs.-D metagenomic pathways met a false discovery rate (FDR) < 0.05. In D vs. A, exploratory screening identified 254 annotated plasma and 338 annotated egg candidates, of which 62 and 80, respectively, also met FDR < 0.05; exact annotation matching identified one shared candidate. Graded TVP inclusion maintained major egg-output traits while producing dose-related shifts in feed use, cecal microbial features, and compartment-specific molecular profiles. At the higher inclusion levels, less favorable feed conversion and the lower late-period shell strength at 9% were the principal practical responses.