Research Of Mechanism And Optimization Of Parameters Of Rice Straw By Ammoniation

This experiment was designed to study the influence of various levels of urea, moisture and reaction time on the nutrition value of rice straw ammoniated, so as to determine the optimal parameters of urea, moisture and time of ammoniation . Moreover, by analyzing the changes of microstructure and fiber content of rice straw ammoniated, the mechanism of ammoniation was discussed.By the quadratic general rotary unitized design, compared with untreated sample, twenty combinations of three factors and five levels were studied the changes of the fiber content of NDF, ADF, CEL and ADL, CP content, microstructure and the 48 hour digestibility of DM, NDF, ADF in goat's rumen.The purpose was to analyze the relation between every factor and the nutrition of rice straw ammoniated. Five levels of urea selected in this experiment were 2.0%, 3.0%, 4.5%, 6.0%, 7.0% dry matter, moisture were 10g, 16g, 25g, 34g, 40g,reaction time were 12d, 18d, 27d, 36d, 42d.According to the quadratic general rotary unitized design, the regression models of urea, moisture, time and NDF, ADF, CEL, ADL, CP, DDM48,DNDF48,DADF48 were set up and parameters were optimized.Results showed:(1) When rice straw were ammoniated, all treatments'fiber content of NDF, ADF, CEL, ADL decreased, the CP content increased, the 48 hour digestibility of DM, NDF, ADF in goat's rumen increased. The result approved that ammoniation can improve the nutrition value of rice straw. (2) With the increasing of the levels of urea, the fiber content of NDF, ADF, CEL, ADL decreased (P<0.05) , the CP content increased (P<0.01) .With the prolong of reaction time ,the CP content increased, the fiber content of NDF, ADF, CEL, ADL decreased ,but the difference was not significant (P>0.05) .With the decreasing of moisture , the decreasing difference of NDF, ADF was not significant (P>0.05) ,the decreasing difference of CEL, ADL was significant in some groups and was not in the others groups, the CP content decreased (P<0.01) .(3)The influence of urea levels on the 48 hour digestibility of rice straw in goat's rumen was primary. DDM48, DNDF48, DADF48 of 6.0% urea were the biggest and they were the smallest at 2.0%urea. The influence of moisture and reaction time on the 48 hour digestibility of rice straw in goat's rumen is minor ( P>0.05 ) .(4) Ammoniation changed the microstructure of rice straw: the microstructural surfaces of rice straw treated by urea presented smooth fibriform and their holes increased. This change would lead to the area of rice straw easily absorb cellulose enzyme , which maked for the utilization of cellulose and the seperation of enzyme. In addition, with the levels of urea enhancing, these holes increased, but they decreased with the levels of moisture and time increasing. (5)According to the results of experiment and the analysis of regression model, and summarizing various optimum parameters of every testing item, the optimum parameters(urea 7.0%, moisture 10%, reaction time 12d) of rice straw treated by urea were determined in this testing condition.