In-vitro Fermentation, Microbial Profile and Methanogenesis of Two Fibrous Feeds as Influenced by Exogenous Fibrolytic Enzymes Xylanase and Combination of Xylanase and Cellulase.

Abstract

A series of experiments was conducted to determine effects of exogenous Xylanase and combination of Cellulase and Xylanase enzymes on in-vitro fermentation of Panicum maximum (PM) and Oryza sativa [Rice straw (RS)] under batch culture system. Xylanase (X) and a mixture of Xylanase and Cellulase (XC) 1:1 ratio were used as enzyme preparations. Four enzyme dosages (50pl /500mgDM (T l), 100pl/500mgDM (T2), 150pl/500m gD M (T3) and 200pl/500 mg DM (T4) were used for two substrates. As the experiment design Complete Randomized Design with three replicates for each treatment, and the incubation period of 24h. was used. Addition of X and XC improved total In vitro gas production (IVGP) significantly (P<0.05) as compared to control for both PM and RS. The highest dose (200p/500m g) of X and XC were associated with the highest IVGP for both PM and RS. Both X and XC improved in vitro dry matter digestibility (IVDMD) of PM and RS significantly (P<0.05) as compared to control. T4 of X had the highest IVDMD in both substrates. T l of XC had the highest IVDMD for PM but for RS it was T3. The total Ammonia-N percentage (NH3-N %) in fermentation liquid was highest for T4 with X for both PM and RS. Maximum NH3-N production was obtained with T3 and T4 for XC for both substrates. Finally it can be concluded, that supplementation of X and XC improved IVDMD of both PM and RS. T4 of X and T l of XC were most effective in digestibility of PM when T4 of X and T3 of XC were effective for digestibility of RS. The results reveal that use of fibrolytic enzymes shown to be an effective way to improve the ruminal fermentation characteristics of fibrous feeds as well as a significant way to reduce methanogenesis. However, further investigations are necessary to identify the correct doses.