Fibrolytic enzymes produced by solid-state fermentation to improve sugar cane silage

Grasses and forages are the principal food source for bovines in the tropic, but forage production varies in quality and quantity throughout the year, directly affecting cattle productivity. An alternative in dry seasons is the use of sugar cane (SC), however it has both low digestibility (20 %) and protein (2.5 to 4.5 %), and also a mineral imbalance. The objective of the present study was to evaluate the use of whole SC in a biotechnological process of solid state fermentation (SSF) with a white rot fungus (Pleurotus sapidus). An evaluation was made of the chemical composition of the SSF on day 0 (CF-0) and 15 (CF-15) and the values of IVDMD, TP, NDF and ADF were: 1) for CF-0, 59.17, 2.53, 50.18 and 31.80 %; 2) for CF-15, 65.08, 6.23, 74.24 and 60.84 %. The enzymatic activity of cellulases, xylanases and laccases was evaluated only for CF-15: 1.96, 2.08 and 5.25 IU g^-1 DM. The whole SC silage included 0, 10 and 20 % of CF-15 and changes were evaluated in its chemical composition at 0, 8 and 16 d of silage. At 16 d the silage presented pH 4.2 and increase (p≤0.05) of lactic acid, acetic acid and NH₃-N; in the treatment with 20 % CF-15 there was higher (p≤0.05) IVDMD (69.19 %) and maximum volume of in vitro gas production (207.09 mL mg^-1 DM). The analysis of the results suggests that solid ferments can be included with P. sapidus to improve the IVDMD and the fermentative variables of whole SC silage.