Treatment of wheat straw using tannase and white-rot fungus to improve feed utilization by ruminants

Shailendra Raghuwanshi,Rajendra Kumar Saxena,Swati Misra

doi:10.1186/2049-1891-5-13

Shailendra Raghuwanshi, Rajendra Kumar Saxena + Show 1 more

Open Access

https://doi.org/10.1186/2049-1891-5-13

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Abstract

BackgroundCurrent research to enrich cattle feed has primarily focused on treatment using white rot fungi, while there are scarce reports using the enzyme tannase, which is discussed only in reviews or in the form of a hypothesis. In this context, the aim of the present study was to evaluate the effect of tannase on wheat straw (WS) and also the effect of lyophilized tannase at concentrations of 0.1%, 0.2%, and 0.3% (w/w) on WS followed by fermentation with Ganoderma sp. for 10 d and compared in relation to biochemical parameters, crude protein (CP) content, and nutritional value by calculating the C/N ratio in order to improve the nutritional value of cattle feed.ResultsPenicillium charlesii, a tannase-producing microorganism, produced 61.4 IU/mL of tannase in 54 h when 2% (w/v) tannic acid (TA) was initially used as a substrate in medium containing (% w/v) sucrose (1.0), NaNO3 (1.0), and MgSO4 (0.08 pH, 5.0) in a 300-L fermentor (working volume 220 L), and concomitantly fed with 1.0% (w/v) TA after 24 h. The yield of partially purified and lyophilized tannase was 5.8 IU/mg. The tannin-free myco-straw at 0.1% (w/w) tannase showed 37.8% (w/w) lignin degradation with only a 20.4% (w/w) decrease in cellulose content and the in vitro feed digestibility was 32.2%. An increase in CP content (up to 1.28-fold) along with a lower C/N ratio of 25.0%, as compared to myco-straw, was obtained.ConclusionsThe use of tannin-free myco-straw has potential to improve the nutritional content of cattle feed. This biological treatment process was safe, eco-friendly, easy to perform, and was less expensive as compared to other treatment methods.

Highlights

Current research to enrich cattle feed has primarily focused on treatment using white rot fungi, while there are scarce reports using the enzyme tannase, which is discussed only in reviews or in the form of a hypothesis
A previous study reported that the selected soil isolate, identified as Penicillium charlesii, produced 61.4 IU/mL in 54 h in 220 L of statistically optimized medium composed of (% w/v) tannic acid (TA) (2.0), sucrose (1.0), NaNO3 (1.0), and MgSO4 (0.08; pH 5.0) contained in 300-L vessel and fed with 1.0% (w/v) TA after 24 h of incubation
The tannase obtained from the fermentation broth was partially purified by ultrafiltration (30 kDa), ammonium sulfate precipitation, and lyophilized with a final yield of 5.8 IU/mg [26]

Summary

Introduction

Current research to enrich cattle feed has primarily focused on treatment using white rot fungi, while there are scarce reports using the enzyme tannase, which is discussed only in reviews or in the form of a hypothesis. In this context, the aim of the present study was to evaluate the effect of tannase on wheat straw (WS) and the effect of lyophilized tannase at concentrations of 0.1%, 0.2%, and 0.3% (w/w) on WS followed by fermentation with Ganoderma sp. The use of WS for ruminant feeding is constrained by its low digestibility of the energy-rich cell walls because of the high silica content, the tannins, lignin, and the relatively low protein and energy content, when fed to cattle as the only feed source it could significantly influence livestock production [5,6]

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