| چکیده انگلیسی مقاله |
The aim of this study was to evaluate the effects of chemical treatments including urea (5%), ammonia (3.5%), calcium hydroxide (4%), sodium hydroxide (5%), sulphuric acid (5%) and hydrogen peroxide (5%) on pH, DM solubility, lignin, silica, phenolic compounds, cellulose and hemicellulose stucture and ruminal degradability of rice straw. After processing, the treated straw was ensiled for 1 month and then analysed for chemical characteristics, Fourier transform infrared spectroscopy (FTIR) analysis, and ruminal degradability (fistulated cows). The results showed that urea treatment showed no considerable effect on chemical compositions and ruminal degradability when compared to untreated straw. Ammonia treatments caused a slight increase in dry matter solubility and neutral detergent fiber (P>0.05) while, the release of phenolic compounds and degradability of NDF were largly enhanced with ammonia treatment (P< 0.01). Improvement in solubility of DM, phenolic compounds and NDF were highest as a result of acidic treatment (P< 0.01). Although, DM degradability was enhanced, inter molecular hydrogen bonds in cellulose microfibrills and NDF degradability was depressed with acid application (P< 0.01). Treatment with hydrogen peroxide increased degree of esterification, showed no effect on chemical characteristics (P>0.05), but decreased significantly DM and, in particular hemicellulose degradability (P< 0.01). The highest improvement in ruminal degradability, silica and phenolic compounds solubilities were achieved with NaOH treatment (P< 0.01). In conclusion, treatment with hydrogen peroxide and sulphuric acid resulted in increased esterification of hemicellulose and in decreased the optima pH for ruminal microbes, respectively while, ammonia and sodium hydroxide treatments showed no adverse impact on the chemical characteristics with a substantial enhancement in ruminal degradability of rice straw |