化学预处理对稻草硅化程度的影响及其对瘤胃降解率的改善效果

本试验结合化学分析与电镜技术,探讨了氨化与碱化处理对稻草硅化程度的影响,分析了稻草硅化程度与降解率的相关性。化学分析显示,碱化或氨化处理稻草的总硅含量随氢氧化钠或碳酸氢铵处理剂量的增加而线性下降(P<0.01);可溶性硅含量随碳酸氢铵处理剂量的增加变化不显著(P>0.05),但随氢氧化钠处理剂量增加线性下降(P<0.01);总硅与稻草干物质降解率间存在极显著负相关(r=-0.560,P<0.01)。电镜观察发现,氢氧化钠处理的稻草茎表皮根毛皱缩、乳突和瘤状结构部分溶解,碳酸氢铵处理的稻草茎外表皮层部分脱落;氢氧化钠处理的稻草茎表皮有明显的降解优势,碳酸氢铵处理的稻草茎表皮瘤胃降解72h后仍保持完整的乳突和瘤状结构。上述结果表明,氨化和碱化处理可以在一定程度上降低稻草的硅化程度,借此提高稻草的降解率,但两者降低稻草硅化的程度与方式不同。氨化处理通过使稻草表皮层部分脱落,降低稻草总硅含量,但借此提高稻草降解率的作用较弱;碱化处理可使稻草表皮硅酸盐部分溶解,从而使稻草总硅含量、可溶性硅含量下降,加速稻草降解。

Improvement of Rumen Degradability along with Changes of Silica of Rice Straw by Chemical Treatments

Chemical analysis and electron microscopy were used to study the effects of chemical pretreatments on silica, and to analyze the relationship between silica content and rumen degradability of rice straw. The chemical analysis showed that total silica content of rice straw was linearly decreased with the increasing dosage of sodium hydroxide (SH) or ammonium bicarbonate (AB) (P<0.01), while the extractable biogenic silica was linearly decreased only with the increasing dosage of SH. There was a significant correlation between total silica and rice straw degradability (r=-0.560, P<0.01). The papillas, wart-like structures, and micro-hairs on the cuticle layer of rice straw stem epidermis were crimpled by SH treatment, but these changes were not observed in AB-treated stem. A part of cuticle waxes silica layer was breached by AB. When the SH-treated stem was degraded in the rumen for 48 h, only vertical ridge-like structure was left. However the epidermis was still observed in untreated and AB-treated stem even after rumen incubation for 72 h. From these results they are inferred that SH treatment decreases the total silica and extractable biogenic silica content with dissolving cuticle wax layer, and hence increases the degradation of this tissue, while the AB treatment is less effective than SH, The cuticle wax layer may be breached by AB treatment, but its degradation could not be greatly improved.