Effect of Ammoniated and/or Basidiomycete White-Rot Fungi Treatment on Rice Straw Proximate Composition, Cell Wall Component, and In Vitro Rumen Fermentation Characteristics

Various pretreatments are employed to increase the utilization of rice straw as a ruminant feed ingredient to minimize its negative environmental impact. However, an efficient alternative is still needed. The purpose of this study was to evaluate the ability of ammonia and/or white-rot fungi (Pleurotus ostreatus) to degrade lignin, increase the nutritional value, and enhance the rumen fermentability of rice straw. Rice straw was treated with ammonia and/or basidiomycete white-rot fungi (P. ostreatus) with untreated straw as control under solid-state fermentation employing a completely randomized design. The crude protein increased from 2.05% in the control to 3.47% in ammoniated rice straw, 5.24% in basidiomycete white-rot fungi (P. ostreatus), and 6.58% in ammoniated-basidiomycete white-rot fungi-treated (P. ostreatus) rice straw. The ammoniated-basidiomycete white-rot fungi-treated (P. ostreatus) rice straw had the least lignin content (3.76%). Ammoniated-basidiomycete white-rot fungi-treated (P. ostreatus) rice straw had improved in vitro dry matter digestibility (65.52%), total volatile fatty acid (76.56 mM), and total gas production (56.78 mL/g) compared to ammoniated rice straw (56.16%, 67.71 mM, 44.30 mL/g) or basidiomycete white-rot fungi-treated (P. ostreatus) rice straw (61.12%, 75.36 mM, 49.31 mL/g), respectively. The ammoniated-basidiomycete white-rot fungi (P. ostreatus) treatment improved rice straw's nutritional value, in vitro dry matter digestibility, volatile fatty acids, and gas production.