Improvement of organic matter digestibility along with changes of physical properties of rice straw by chemical treatments

J Ye,Y Wu,J Wang,J Liu

doi:10.22358/jafs/66875/2006

Abstract

This study was carried out to study the effects of different chemical treatments on physical properties and digestion of rice straw. Rice straw was treated with sodium hydroxide (NaOH) at 15, 30, 45, 60 or 75 g/kg dry matter, ammonia bicarbonate (NH 4 HCO 3 ) at 30, 60, 90, 120 or 150 g/kg or their combinations (10 or 20 g NaOH/kg and 30, 60 or 90 g NH 4 HCO 3 /kg), respectively. The relationship between straw digestion and its physical properties was analysed. Treatment with NaOH increased the volumetric weight (VW), swelling capacity (SC), water-holding capacity (WHC), and in vitro organic matter digestibility (OMD), and decreased specific porosity (SP) of rice straw linearly. Treatment with NH 4 HCO 3 did not significantly affect VW, SC, or SP, but increase OMD linearly and tended decrease WHC. For the combination treatment of NaOH and NH 4 HCO 3 , there existed significant interactions on SC, SP and OMD. A significant linear correlation was found between OMD and VW, SC, SP, or WHC, when the data for all treatments were analysed. The accuracy of regression equation could be improved by including multiple physical property parameters. It is inferred that change in all physical properties is indicative of improvement in straw digestion after treatment.

Highlights

In China, annual yield of rice straw totals currently about 188 million tonnes (Guo et al, 2002)
Changes in chemical compositions of rice straw by NaOH, NH4HCO3, and their combination treatment are presented in Tables 1, 2 and 3, respectively
The effects of NaOH on Neutral detergent fibre (NDF), acid detergent lignin (ADL), crude protein (CP), and ash, and of NH4HCO3 on CP were significant (P

Summary

INTRODUCTION

In China, annual yield of rice straw totals currently about 188 million tonnes (Guo et al, 2002). It has been found that alkali treatment may reduce the lignification of straw (Xiao et al, 2001), cleavage the ester and ether linkages between hemicellulose and lignin (Lawther et al, 1996), decrease the crystallinity of cellulose (Goto and Yokoe, 1996; Isogai and Usuda, 1996), and weaken the interlinkage of the silica-covered cuticle with underling tissues (Bae et al, 1997). This study was conducted to investigate the effects of NaOH, NH4HCO3 or their combination treatments on physical parameters of rice straw, such as volumetric weight, swelling capacity, specific porosity and water-holding capacity, and to analyse relationships between physical properties and digestion of straw

MATERIAL AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS