Influence of Fibrolytic Enzymes on the <i>in vitro</i> Hydrolysis and Fermentation of Different Types of Roughages Treatment

Abstract

The effects of pre-treating different types of roughages with alkali on the efficacy of exogenous fibrolytic enzymes for improving their digestibility were studied <em>in vitro</em>in factorial arrangement 4 × 3 × 5 (enzyme, treatment and roughage types). Two fibrolytic feed enzymes novozyme (N) and celloclast (C) their combination (N+C) were evaluated for their potential to improve <em>in vitro</em>degradation of different roughages including two straws (wheat straw: WS; barley straw: BS), grass hay (GH), corn stover (CS) and corn cobs (CC) as untreated or alkaline treated (NaOH or urea). The enzyme products were in liquid form and applied at a rate of 1 mg enzyme protein/g DM substrate. Anaerobic buffer medium and strained ruminal fluid were added to the <em>in vitro</em>incubations. Degradabilities of dry matter (DM), neutral detergent fibre (NDF), cellulose, soluble protein and reducing sugar profiles were determined at the end of the 24 h incubation. Overall NDF degradability of roughages were slightly increased by alkaline treatment (P<0.05) but, the addition of fibrolytic enzymes directly to the ruminal fluid at the application rates could not increase significantly DM or cellulose degradation (P>0.05). Use of fibrolytic enzymes released higher amounts of reducing sugars and lower soluble protein compared to control (P<0.05). Alkali treatment increased (P<0.05) the degradability of DM and fiber degradability. It was higher in NaOH treated forage compared to urea treated forages (P<0.05).