The effect of a chemical treatment (ammoniation with urea) or a biological treatment (innoculation with the fungus Pleurotus ostreatus) on the nutritive value of Brachiaria decumbens hay was evaluated by means of chemical analyses and a digestibility trial with sheep. Both treatments lasted 42 days, and thereafter the hay was dried and ground for animal feeding. The experimental diets were the following: untreated Brachiaria hay (FNT); untreated hay plus urea added in the trough (FNT+U); fungus-treated hay plus urea (FTB+U); and ammoniated hay plus untreated hay (FTQ+FNT). The FNT+U, FTB+U and FTQ+FNT diets were isonitrogenous. Both the chemical and biological treatments caused changes in hay chemical composition. Ammoniation raised crude protein (CP) and acid detergent fiber (ADF) contents and reduced both hemicellulose(HEM) content and the proportion of hemicelullose in cell walls (HEM-NDF). The biological treatment tended to raise CP; it increased ADF, lignin (LIG), cellulose proportion in cell walls (CEL-FDN) and lignin proportion in cell walls (LIG-FDN); it reduced neutral detergent fiber (NDF), HEM and HEM-NDF. However, it reduced dry matter (DM), NDF, cellulose (CEL) and FDA digestibility; however, it increased intake, probably due to smaller NDF content and smaller particle size, causing a higher rate of passage. Both the biological and chemical treatments are important alternatives in increasing the nutritive value of lignocellulosic materials. Nevertheless, the results obtained in this experiment were not satisfactory.
biological treatment; Brachiaria decumbens; cell walls; chemical treatment; lignin; "organic" products
