【摘要】：甘蔗渣是甘蔗制糖的三大副產物之一,目前主要用于燃燒和造紙,利用率較低。甘蔗渣具有價格便宜、數量龐大、成分穩(wěn)定和來源集中等特點,用于生產反芻動物粗飼料具有極大的前景。然而,由于甘蔗渣中木質素含量過高,且木質素可與纖維素和半纖維素會形成致密木質纖維結構,導致微生物和酶利用率低,不宜直接應用于生產高品質粗飼料。故本研究以甘蔗渣為原料,利用氫氧化鈉/尿素預處理,降低木質素含量和提高其可發(fā)酵性。隨后,通過青貯方式對預處理后甘蔗渣進行發(fā)酵,并探索添加劑及調制條件對青貯品質的影響。通過對比單一氫氧化鈉和氫氧化鈉/尿素兩種方法對甘蔗渣的預處理效果,實驗結果表明兩種方法均對降解木質素和提高酶解率有顯著作用。其中氫氧化鈉/尿素混合預處理木質素降解率為61.83%,纖維素酶解率為72.68%。通過響應面試驗優(yōu)化得到氫氧化鈉/尿素降解甘蔗渣的最佳條件為:尿素濃度為10.50%、氫氧化鈉濃度為4.44%、預處理時間為6.3 h、處理溫度為60℃。以此條件進行預處理后的甘蔗渣木質素降低了 62.45%,纖維素提升了 65.27%,酶解后還原糖量為0.518 g/g(相對于甘蔗渣)。向預處理后的甘蔗渣中添加乳酸菌及纖維素酶,以提高青貯品質,結果表明:添加乳酸菌或纖維素酶均有利于提高青貯效果。二者混合添加的試驗組青貯后pH降低至4.27,乳酸含量、可溶性糖含量和干物質粗蛋白含量分別提高了 56.52%、61.15%和42.22%,氨態(tài)氮/粗蛋白(NH3/TN)、中性洗滌纖維(NDF)和酸性洗滌纖維(ADF)分別下降了 26.89%、12.08%和 5.04%。通過正交試驗對不同調制條件下甘蔗渣青貯飼料品質和營養(yǎng)成分指標進行了分析,得出因素影響作用大小依次為:甘蔗渣水分含量粉碎粒徑糖蜜添加量,并由此得到的最佳調制條件為:甘蔗渣含水量60%-65%、粉碎粒徑為2.36 mm、糖蜜添加量為9%。在此條件下得到的青貯飼料pH值為4.22,乳酸/總酸為66.41%,NH3/TN為4.81%,干物質中粗蛋白含量為3.60%,NDF 和 ADF 分別為 68.21%和 56.07%。
[Abstract]:Bagasse is one of the three by-products of sugarcane sugar making, which is mainly used in burning and papermaking. Bagasse has the characteristics of low price, large quantity, stable composition and concentrated source, so it has great prospect in producing ruminant forage. However, because the lignin content in bagasse is too high and lignin can form dense wood fiber structure with cellulose and hemicellulose, the utilization ratio of microorganism and enzyme is low, so it is not suitable to be directly used in the production of high quality crude feed. Therefore, using bagasse as raw material, sodium hydroxide / urea pretreatment was used to reduce lignin content and improve its fermentability. After that, bagasse was fermented by silage, and the effects of additives and modulation conditions on the quality of the silage were explored. The pretreatment effects of single sodium hydroxide and sodium hydroxide / urea on bagasse were compared. The results showed that both methods had significant effects on lignin degradation and enzymatic hydrolysis. The lignin degradation rate was 61.83% and the cellulolysis rate was 72.68% after mixed pretreatment with sodium hydroxide / urea. The optimum conditions for the degradation of bagasse with sodium hydroxide / urea were obtained by response surface test: urea concentration was 10.50, sodium hydroxide concentration was 4.44, pretreatment time was 6.3 h, treatment temperature was 60 鈩，

本文編號：2217773