Different Milling Byproduct Supplementations in Mushroom Production Compost Composed of Wheat or Rice Straw Could Upgrade the Properties of Spent Mushroom Substrate as a Feedstuff

Abstract

Wheat bran (WB), barley flour (BF), rice bran (RB), wheat red dog (WRD) or reduction shorts (WRS) supplementation, as a food supplement (FS, 19%), to mushroom composts having wheat (WS) or rice straw (RS) as basal substrate (BS, 80%) could have contributed to improving the nutritional value and forage quality properties of spent mushroom substrate (SMS). The SMSs from king oyster mushroom ( Pleurotus eryngii ) production were evaluated with 2 BS (WS and PS) x 5 FS (WB, BF, RB, WRD, or WRS) factorial arrangement design. The BS x FS interaction significantly affected some of the studied variables (nutrient contents and in vitro true digestibility, relative feed value, and relative forage quality) of the SMSs used to be evaluated as a feedstuff. The BS significantly affected the acid detergent lignin content, digestible dry matter, metabolizable energy, estimated net energy, and total digestible nutrients. In contrast, the FS affected the acid detergent lignin content and net energy lactation value. In conclusion, independent of FS, WS-based SMSs and the BF and WRD supplemented-SMSs independent of BS had higher nutritional value and forage quality properties than other SMSs. Therefore, these SMSs could be exploited post-cultivation as animal feed due to their upgraded properties.