Ruminal Fungi Colonisation of Stem Tissue of Untreated and Urea Treated Rice Straw Varieties

Abstract

The study was conducted to investigate the digestibility untreated and urea treated rice straws varieties from ruminal fungi colonization in the rumen of sheep. The study used straw from 3 varieties of rice namely Illabong, Dongara and Yrm varieties which represented medium and low quality of straw. Each varieties of straw were treated with urea prior incubation in the rumen. Approximately 5mm of 10 cross section of untreated and urea treated straw stem internodes were taken below flag leaves. The materials was placed in nylon bag and incubated in the rumen of fistula sheep for 24, 48 or 72 hours. After withdrawn from the bag bags were washed then samples were removed from bags and observed under scanning electron microscopy (SEM). Observation under SEM revealed that sporangia ruminal fungi had colonised the Dong and Yrl varieties after both 48 and 72 hours incubation. The substrate of Ilb was colonised after 24 and 72 hours incubation. All population tended to be lower after 72 hours incubation than the shorter incubation. Urea treatment decreased the time required for ruminal fungi colonisation. All treated samples were colonised after 24 hours of incubation. From this study can be concluded that digestibility variation due to urea treatment could be explained from ruminal fungi colonisation but not with rice straw varieties.