Bioconversion in Ryegrass-Fescue Hay by Pleurotus ostreatus to Increase Their Nutritional Value for Ruminant

Carbohydrates from lignocellulosic feed can be released by basidiomycete fungi for ruminal fermentation. This study aimed to evaluate the bioconversion of hay of ryegrass-fescue (Lolium perenne-Festuca arundinacea) by solid state fermentation with Pleurotus ostreatus, to obtain superior quality hay. After only 14 days of fermentation, crude protein (CP) (4.73 to 5.16%), and non-fibrous carbohydrates (NFC) (20.84 to 25.04%) increased, while neutral detergent fiber (NDF) (68.72 to 64.87%) and acid detergent lignin (5.88 to 1.98%) decreased. The enzymatic biodegradation carried out by P. ostreatus was verified, through measurements of enzymatic activity. Lignin peroxidase (LiP) and laccase (Lac) reached the higher activity on day 14 (19.51 U/L and 34.17 U/L, respectively), whereas manganese peroxidase (MnP) displayed stability up to 21 days of fermentation (between 6.54 and 7.75 U/L). In conclusion, results indicate that lignocellulosic feed bioconversion by P. ostreatus is promising to improve the ruminal fermentation of fibrous feedstocks and 14 days were considered to be optimal for hay fermentation.