The Bioavailability of Solid-State Fermented Feather Meal Using a Novel Feather-Degrading Bacterium Bacillus...

In this study, an effective feather-degrading bacterium was isolated and the solid-state fermentation condition for feather degradation was optimized. The resulting fermented feather meal (FFM) was evaluated for its bioavailability in broilers. Four Bacillus strains were examined for feather degradation rates, with Bacillus velezensis PN1 exhibiting the highest rate (83.24%, p < 0.05). A 3 × 3 × 3 factorial design was used to test substrate moisture content (45%, 55%, 65%), temperature (27 °C, 37 °C, 47 °C), and incubation time (24, 48, 72 h) for optimized fermentation conditions. In vitro pepsin digestibility (IVPD) revealed a significant interaction between temperature and time (p < 0.05), and the optimal performance was achieved at 37 °C for 72 h, followed by 37 °C for 48 h. Considering production time and cost, FFM2 (produced with 65% moisture at 37 °C for 48 h) was further compared with FFM1 (produced under the same conditions but at a lower temperature of 27 °C), and commercial hydrolyzed feather meal (HFM). IVPD did not differ significantly between FFM1, FFM2, and HFM, as they all showed significantly higher digestibility compared to raw feathers (RFs). FFM1, as well as FFM2, had significantly higher histidine and lysine concentrations than RF (p < 0.05), while FFM2 had a significantly lower cysteine content (p < 0.05). Based on fermentation conditions and amino acid composition, FFM2 was considered more suitable for large-scale production and was used in a broiler growth trial. The inclusion of 5% FFM2 in the broiler diet did not significantly affect body weight at 35 days compared to the 5% HFM group (p > 0.05), although both groups showed significantly lower weight gain than the 5% fish meal (FM) group (p < 0.05). The feed conversion ratio and performance efficiency factor did not differ significantly between the FFM2, HFM, and FM groups (p > 0.05). In groups fed diets without supplemental crystalline amino acids, growth performance did not significantly differ between the HFM and FFM2 groups (p > 0.05), although both performed significantly worse than groups with amino acid supplementation. In conclusion, FFM produced by B. velezensis PN1 through solid-state fermentation enhances feather bioavailability in poultry and can completely replace HFM when included at 5% in broiler diets, offering a potential sustainable alternative for poultry nutrition on a commercial scale.