Addition of cell wall degrading enzyme and wheat bran on fermentation characteristics and in vitro gas production of ensiled rice straw

A two way factorial experiment was designed to study the technique aspects of ensiling rice straw (RS) mixed with Strawzyme (an experimental preparation of cell-wall degrading enzymes) and wheat bran (WB). The WB was added at levels of 0, 3, 6 or 9% (fresh basis), respectively, and the RS was untreated (C-0, C-3, C-6 and C-9), or treated with Strawzyme at level of 1300 g/t DM (T-0, T-3, T-6 and T-9). Addition of WB improved the fermentation quality and nutritive value of RS silage. The pH value, percentage of ammonia N in total N and butyrate content were decreased, and lactate content and in vitro gas production (GP) increased with the increasing levels of WB. Enzyme treatment decreased the neutral detergent fibre, pH, ammonia-N and butyrate, and increased lactate and in vitro GP. There were significant interaction effects on pH, lactate and butyrate content between enzyme and WB. Therefore the silages in T-6 and T-9 showed good quality with lowest pH and highest lactate as well as no any butyrate. Proportion of ammonia N of total N was decreased by 37.9 or 15.5%, and the lactic acid was increased by 67.8 or 5.7%, respectively, when Strawzyme plus 6 or 9% WB was added. It can be concluded that combination of Strawzyme with WB was more effective in the improvement of RS silage quality than addition of WB alone.