Fermented Gallus gallus foot keratin–bone composites as peptide–mineral concentrate for aquafeed: ratio-dependent proximate compositional data

Significant compositional differences were observed among treatments (Wilks' Λ = 4.64 × 10⁻¹², p < < 0.001), with large effect sizes for all parameters (η² ≥ 0.87). The highest protein content (76.67%, dry weight) occurred in exclusive keratinous biomass, whereas ash content peaked at 26.26% in exclusive bone residues. Moisture, protein, fat, and fiber positively covaried (r ≥ .934) and contrasted strongly with ash (|r| ≥ 0.905). Formulations may therefore be theoretically tuned to align with dietary strategies for certain ontogenetic stages, pending validation against species-specific requirement data and feeding trials. Validation through in vivo digestibility and amino acid profiling is further recommended; without such validation, the findings remain preliminary and limited to compositional characterization.