Cao Xiaohui, Zuo Sasa, Lin Yanli, Cai Rui, Yang Fuyu, Wang Xuekai, Xu Chuncheng
College of Engineering, China Agricultural University, Beijing 100083, China.
College of Grassland Science and Technology, China Agricultural University, Beijing 100093, China.
Animals (Basel). 2023 Dec 21;14(1):29. doi: 10.3390/ani14010029.
The hard texture and poor palatability of straw are important factors that hinder its application in feed. Expansion is a technology that can improve the utilization of biomass, but few studies have comprehensively revealed how to change physicochemical characteristics to improve nutritional value. In this study, mechanical and chemical methods were combined to study the texture properties, rheological properties, and physicochemical structures of straw, and its utilization value was evaluated by in vitro rumen digestion. Expansion caused hemicellulose degradation, cellulose separation, and lignin redistribution, resulting in a decrease in crystallinity. The hardness and chewiness of expanded straw were reduced by 55% to 66%, significantly improving palatability. The compressive stress could be reduced by 54-73%, and the relaxation elasticity was reduced by 5% when expanded straw was compressed. The compression deformation of expanded straw was doubled compared to feedstock, and the compacting degree was improved. Expanded straw significantly improved digestibility and gas production efficiency, which was due to the pore structure increasing the attachment of rumen microorganisms; besides that, the reduction of the internal structural force of the straw reduced energy consumption during digestion. The lignin content decreased by 10%, the hardness decreased further in secondary expansion, but the digestibility did not improve significantly.
秸秆质地坚硬且适口性差是阻碍其在饲料中应用的重要因素。膨化是一种可提高生物质利用率的技术，但鲜有研究全面揭示如何通过改变物理化学特性来提高营养价值。本研究将机械法和化学法相结合，研究秸秆的质地特性、流变特性和物理化学结构，并通过体外瘤胃消化评估其利用价值。膨化导致半纤维素降解、纤维素分离和木质素重新分布，致使结晶度降低。膨化秸秆的硬度和咀嚼性降低了55%至66%，适口性显著提高。膨化秸秆压缩时，压缩应力可降低54 - 73%，松弛弹性降低5%。与原料相比，膨化秸秆的压缩变形增加了一倍，压实度提高。膨化秸秆显著提高了消化率和产气效率，这是由于孔隙结构增加了瘤胃微生物的附着；除此之外，秸秆内部结构力的降低减少了消化过程中的能量消耗。木质素含量降低了10%，二次膨化时硬度进一步降低，但消化率未显著提高。
