345 Bioconversion Treatment of Corn Stover Can Create Cheap Feed Resource for Limited Resource Farmers

Abstract

Abstract The study aimed to improve the nutritive value of corn stover to provide a viable and sustainable source of cheap feed resource for ruminant production since feed is the single largest cost in any livestock enterprise. Corn stover is the largest non-food biomass available in the United States. It could be a low-cost feed, but high lignocellulose content limits both digestibility and nutritive value. Some fungi, especially white rot fungi (WRF), are known to selectively degrade fiber lignin and secrete bioactive compounds that could benefit digestibility and feed value. Pleurotus ostreatus is a mushroom-forming WRF. We tested corn stover fermented with P. ostreatus for improvement in nutrients and digestibility (Table 1). Two ruminally cannulated dairy cows were used in an in vitro study to test the effect of P. ostreatus use in solid state fermentation on the chemical composition in corn stover. The experiment was 2 x 3 factorial design with 4 replicates sampled at 6, 24 and 48 h on treated and untreated (control) corn stover. The dry matter disappearance (DMd) and volatile fatty acid (VFA) production (Table 2). Treatments were 1) untreated corn stover as control, and 2) corn stover treated with P. ostreatus. Crude protein (CP) and ash were significantly (P < 0.001) impacted with 52.9 and 31.2% increment in CP and ash respectively for treated samples. We noted an increase (P < 0.001) of 106 to 681% in microbial yield in treated vs untreated samples which demonstrated a greater potential for increased microbial protein synthesis. Acid detergent fiber, neutral detergent fiber and hemicellulose were significantly reduced (P < 0.001) by 6.71, 18.2 and 37.8%, respectively for the treated samples. Non-fiber carbohydrate was significantly (P < 0.001) impacted with a 118% increment and both DMd and total VFA were significantly (P < 0.001) greater, ranging between 40.9 to 240% and 5.85 to 11.2%, respectively (Table 3). Additionally, the rumen fermentation pathway favored the production of propionate with a significant (P < 0.001) treatment and time effect that resulted in 9.37 - 14.0% increment in propionate production for the treated samples. Consequently, a significant (P < 0.001) effect was observed in acetate production with 1.76 - 4.01% reduction, which resulted in 7.09 - 11.42% reduction in A:P ratio for the treated samples (Table 4). The study showed that bioconversion can improve the feeding value of corn stover to provide an economical novel feed resource, and that corn stover spent mushroom substrate could potentially substitute conventional feeds to support animal requirements. Although actual cow performance remains to be determined experimentally via feeding studies, we are convinced that bioconversion of agricultural waste from crop farming could be a functional system approach to alleviate the feed cost challenges faced by socially disadvantaged and limited-resource farmers.