Research And Optimization Of Efficient Degradation Technology Of Reed Lignocellulose

In recent years,according to the continuous development of China’s livestock breeding industry,feed demand is increasing year by year,and the shortage of bulk feed materials has become an important factor limiting the sustainable development of China’s livestock industry.Straw feedstuffs are rich in lignocellulose and can be used as non-conventional feedstuffs to replace staple foods after reasonable development,alleviating the current situation of food competition between humans and animals.Reed is widely available,low cost,with an annual production of 1 million tons,and high nutrient content.After treatment,it can be used as a source of roughage for ruminants such as cattle and sheep,and can also be partially added to pig feed.The key to efficient utilization of reed and other straw-like resources is to efficiently degrade the lignocellulose of straw and its cross-linked structure,and to improve the efficiency of cellulase enzymatic digestion of straw and animal digestibility.In this study,we analyzed the conventional nutrient composition of reeds from six different growth periods in major reed production areas in Tianjin,and degraded the lignocellulose of reed straw by steam blasting,chemical treatment and combined treatment,optimized the process conditions of chemical treatment by Box-Behnken response surface method,and investigated the effect of different treatments on the degradation of lignocellulose of reed straw by scanning electron microscopy,Fourier infrared spectroscopy,X-ray diffraction and cellulase enzymatic digestion test.The experimental results can provide an important theoretical basis and technical support for the efficient degradation of lignocellulose from reed and other straw materials and the high-value utilization of non-conventional feed resources,which can provide an effective solution to alleviate the shortage of feed resources.The main results are as follows:1.Analysis of the conventional nutrient composition of reed at different growth periods.The crude protein（CP）,crude ash,calcium（Ca）,and phosphorus（P）contents of reed showed a decreasing trend from the leaf-spreading stage to the dead leaf stage;the dry matter（DM）and acid detergent lignin contents showed an increasing trend;the neutral detergent fiber（NDF）and acid detergent fiber showed a decreasing trend followed by an increasing trend;the total energy（GE）and crude fat（EE）contents showed a decreasing trend followed by an increasing trend followed by a decreasing trend.The DM content,CP content,NDF content,Ca content and P content of reed at the tassel stage were not significantly different from those at the later stage of growth and remained at a good level;the EE content and GE content were not significantly different from those at the flowering stage and reached the highest level throughout the growth period.The analysis of the nutritional value and palatability of the reed showed that the reed has the greatest potential for fodder exploitation during the tassel stage.2.Process optimization of calcium oxide（Ca O）and sodium carbonate（Na₂CO₃）degradation of reed straw lignin and lignocellulose structure analysis.Process optimization of chemical treatment（Ca O and Na₂CO₃）for degradation of reed straw lignin and structural analysis of lignocellulose.（1）The optimal processes for Ca O and Na₂CO₃ degradation of lignin in reed straw during the tassel stage and dead leaf stage were（2%Na₂CO₃,material-liquid ratio 1:3）:Ca O addition 8.08%,time4.63 h,temperature 46.17℃,when the lignin removal rate was 22.10%;Ca O addition8.44%,time 5.52 h,temperature 49.58℃,when the lignin removal rate was 23.75%.（2）The surface structure of reed straw in both periods was destroyed after chemical treatment,and the pores increased and enlarged;the intensity of absorption peaks corresponding to hemicellulose and lignin-related chemical bonds were reduced;the relative cellulose crystallinity index（Cr I）of reed straw changed from 28.69%to 35.94%in the tassel stage and from 37.21%to 46.66%in the dead leaf stage.（3）The reducing sugar content of reed straw at the tassel stage increased significantly（P<0.05）and the glucose enzymatic yield increased by 9.18%after chemical treatment.The results indicated that Ca O and Na₂CO₃（optimized process）could efficiently degrade the lignocellulose of reed straw and change the structural characteristics of reed straw lignocellulose,enhancing the efficiency of cellulase enzymatic digestion of reed straw.3.Investigation of the effect of steam blasting and combined treatment（steam blasting combined with chemical treatment）on reed straw during the heading stage.（1）After steam blasting and combined treatment,the cellulose,hemicellulose and lignin contents of reed straw were significantly reduced（P<0.05）;the reducing sugar content was significantly increased（P<0.05）;the glucose enzymatic yield was increased by 28.70%and 29.96%,respectively.（2）After steam blasting and combined treatment,the surface structure of straw was destroyed and cellulose vascular bundles were significantly exposed;the Cr I values changed from 28.69%to 38.01%and 46.66%,respectively;the chemical structure of lignocellulose was significantly changed after combined treatment.The results showed that steam blasting and combined treatment could degrade the lignocellulose of reed straw efficiently,significantly change the structural characteristics of reed straw lignocellulose and improve the efficiency of cellulase enzymatic digestion.Both Ca O and Na₂CO₃（optimized process）and steam blasting treatments can efficiently degrade the lignocellulose of reed straw and improve its cellulase enzymatic efficiency.Steam blasting followed by Ca O and Na₂CO₃ treatment showed limited improvement in treatment effect.