Nutraceutical Enrichment of Animal Feed by Filamentous Fungi Fermentation

There is an urgent need for improvements in animal production, particularly for ruminants, such that more sustainable and efficient processes are developed for obtaining more nutritious and efficient feeds. Filamentous fungi can add value to residual plant biomass, and may also have the potential to produce metabolites and enrich plant biomasses used in animal nutrition, converting them into nutraceutical sources. Thus, in this work, filamentous fungal fermentation of ruminant feed biomasses commonly used in Brazil was performed, and the enrichment for bioactive metabolites was tested. For this, Fistulina hepatica, Ganoderma lucidum, Pleurotus pulmonarius, Panus lecomtei, and Aspergillus terreus were grown for 28 days on different substrates: starchy grains- (sorghum, oat, and corn), fibrous substrates (coast-cross, rice husk, and moringa plant) and protein-rich substrates (cottonseed cake and pigeon pea plant). Fermented substrates were evaluated for laccase activity, crude protein, beta-glucan, and lovastatin content. The highest growth rate was observed for G. lucidum in oat substrate (OT-01) (0.708 +/- 0.035 cm/day) and F. hepatica in oat + coast-cross + pigeon pea treatment (OT-10) (0.607 +/- 0.012 cm/day). High laccase activity was observed for P. lecomtei grown in starchy grain + moringa + pigeon pea substrate, reaching an activity of 416.8 +/- 20.28 U/g. A. terreus growth in ST-09 (sorghum + pigeon pea) showed higher protein (15.3 +/- 0.46%), beta-glucan (503.56 +/- 8.6 mg/g) and lovastatin (1.10 +/- 0.17 mg/g) content compared to untreated substrates. These results demonstrate that filamentous fungi are an alternative for nutraceutical enrichment of ruminant feed biomasses. To the best of our knowledge, this is the first report in which P. lecomtei and F. hepatica are evaluated for their ability to be cultivated in ruminant feed substrates from Brazil.