Solid-State Fermentation with a Six-Strain Composite Inoculant Reallocates Nutrients in Complete Feeds for Growing-Finishing Pigs and Laying Hens

Solid-state fermentation (SSF) with multi-strain inoculants is widely used to upgrade complete feed, yet how it reallocates nutrients in starch–protein diets has rarely been quantified on a dry-matter basis. Complete feeds for growing-finishing pigs and laying hens were inoculated with a six-strain composite inoculant (two Bacillus strains, two lactic acid bacteria and two yeasts) and fermented anaerobically for 5 d (n = 3; uninoculated feed as received served as the control, n = 1). Both feeds acidified to pH ≈ 4.5. The soluble-protein-to-crude-protein ratio rose by 36.7% and 36.8%, and acid-detergent insoluble protein fell by 21.4% and 23.1%. Soluble carbon was consumed: starch decreased by 17.4% and 3.9%, and linolenic acid by 70.5% and 24.2%, with the magnitude of starch loss tracking the fermentable-carbon supply of each feed. Dry-matter loss concentrated crude protein, ash and fiber fractions, while total digestible nutrients changed by only −2.1% and −1.4%. None of the six strains showed hemolysis (γ-hemolysis) on sheep-blood agar. Fermentation therefore raised protein availability rather than protein quantity, consumed starch and essential fatty acids, and left energy essentially unchanged; the inoculant may be better suited to ruminant roughage than to complete feed.