作物秸秆剪切力与其饲料营养特性的关系

【目的】研究玉米秸、小麦秸和稻草剪切力与其形态学指标、营养成分和瘤胃降解率之间的关系。【方法】选用成熟期收获的玉米秸、小麦秸和稻草，分别测定其秸秆的剪切力，同时测定秸秆的直径、茎厚与线性密度（单位长度重量）及其营养成分含量，采用尼龙袋法测定秸秆干物质（dry matter，DM）、中性洗涤纤维素（neutral detergent fiber，NDF）和酸性洗涤纤维素（acid detergent fiber，ADF）的瘤胃降解率。【结果】试验中3种秸秆收获时的剪切力、形态学指标（线性密度、直径和茎厚）及剪切力/线性密度均差异显著（P＜0.05）。玉米秸、小麦秸和稻草的剪切力与其线性密度、直径和茎厚均呈高度正相关（P＜0.001）。3种秸秆的线性密度与剪切力的相关性最高（P＜0.05），且以剪切力反映玉米秸线性密度的灵敏程度最高。3种秸秆中的营养成分含量及其营养成分（DM和 NDF）瘤胃降解率与剪切力均有不同程度的相关性，且剪切力预测秸秆型粗饲料NDF瘤胃降解率最精准。剪切力较适于预测玉米秸和稻草的营养成分含量及其瘤胃降解率。【结论】作物秸秆剪切力与其饲料营养特性存在相关性。剪切力可不同程度地预测玉米秸、小麦秸和稻草的营养物质含量、物理性状及养分（DM、NDF和ADF）瘤胃降解率的大小，且3种秸秆中剪切力较适于预测玉米秸和稻草的营养价值评定。选用剪切力评定作物秸秆的营养价值，其灵敏程度不同，需根据秸秆种类确定预测模型。

Correlations of Shearing Force and Feed Nutritional Characteristics of Crop Straws

【Objective】This experiment was conducted to study the correlations of shearing force and feed characteristics(morphological characteristic,chemical compositions and in situ digestibility) of corn stalk,wheat straw and rice straw.【Method】 Shearing force was measured with portable shear force apparatus when the corp straws were harvested.Meanwhile,diameter,thickness,linear density(weight per unit length of stem),and chemical composition of straws were measured.Nylon bags and three small-tail Han sheep were used to determine the in situ digestibility of dry matter(DM),neutral detergent fiber(NDF) and acid detergent fiber(ADF) of corn stalk,wheat straw and rice straw.【Result】 The results showed that there were significant differences of shearing force,morphology indicators(linear density,diameter,and thickness) and shearing force/linear density of the three straws at harvest-time(P<0.05).There were positive relationships between linear density,diameter,and thickness and their shearing force of the three straws(P<0.001).Linear density had the highest sensitivity for shearing force of three straws.Moreover,linear density of corn stalk had the highest sensitivity for its shearing force(P<0.05).There were different degrees of correlation between nutritional ingredient and shearing force(P<0.05).In addition,in situ digestibility of nutritional ingredient(DM and NDF) was related to shearing force with different degrees.Shearing force reflects the highest degree of NDF digestibility of corn stalk.Shearing force is the preferable means to predict the nutrients and its rumen degradability of corn stalk and rice straw.【Conclusion】 There were correlations between shearing force and feed characteristics of crop straws.Nutrient content,morphological index and rumen degradability of nutrients(DM,NDF and ADF) can be predicted by shearing force varying degrees.Shearing force can be used as an indicator of nutritive value of corn stalk and rice straw more suitably.Shearing force can be employed to predict the nutritive value of corp straws,while take different varieties into consideration for their sensitivity variance.