紫花苜蓿和黑麦草茎形态学、化学组成和养分瘤胃降解率与剪切力的相互关系

 【目的】研究盛花期紫花苜蓿与灌浆期冬牧70黑麦草茎形态学、化学组成及养分48 h瘤胃降解率与剪切力之间的相关性。【方法】采集2种牧草后,测定茎直径、长度、重量和线性密度,测定剪切力、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、木质素、纤维素及半纤维素含量,用尼龙袋法测定干物质(DM)、中性洗涤纤维(NDF)48 h瘤胃降解率,比较各项指标随茎直径变化的规律,探讨剪切力与各项指标之间的相关性。【结果】盛花期紫花苜蓿茎的线性密度、剪切力、木质素含量随直径增大而提高,直径、线性密度、木质素含量与剪切力均呈线性正相关(P＜0.01);含水量随直径增大而降低,两者之间存在线性负相关(P＜0.01);DM、NDF 48 h瘤胃降解率与剪切力存在线性负相关(P＜0.05)。灌浆期黑麦草茎的茎厚、线性密度、酸性洗涤纤维(ADF)、木质素、纤维素、含水量、剪切力均随着外直径的增大而提高,外径、茎厚、线性密度、ADF、木质素和含水量均与剪切力呈线性正相关(P＜0.05);DM、NDF 48 h瘤胃降解率与剪切力无相关性(P＞0.05)。【结论】对于盛花期紫花苜蓿及灌浆期冬牧70黑麦草,茎剪切力受形态学指标、化学组成的综合影响;紫花苜蓿茎剪切力与DM、NDF48 h瘤胃降解率之间存在显著负相关,因此可用剪切力估计紫花苜蓿茎养分降解率的大小。黑麦草茎剪切力与养分降解率之间无显著相关。

Correlations Among Shearing Force, Morphological Characteristics, Chemical Compositions, and in situ Degradibility of Alfalfa Stem and Rye Grass Stem

【Objective】 The objectives of this study were to investigate the relationships of shearing force with morphological characteristics, chemical compositions, and in situ degradability in 48 h of alfalfa (Medicago sativa L.) stem and Dongmu-70 rye grass (Secale cereale L.) stem. 【Method】 The diameter, length,weight and linear density of stem were measured after sample collection. Shearing force was measured. Meanwhile, the content of moisture were measured, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, cellulose and hemicellulose were measured. Three Xiaowei sheep were used to determine in situ degradability in 48 h of DM and NDF of alfalfa stem and rye grass stem. 【Result】 The results showed that linear density, shearing force and lignin content of alfalfa stem increased as diameter increased. There were positive relationships of shearing force with diameter, linear density, and lignin content of alfalfa stem (P＜0.01). A negative correlation was found between shearing force and moisture content (P＜0.01). Negative correlations also were found between shearing force and DM degradability, NDF digestibility of alfalfa stem (P＜0.05). Linear density, stem thickness, ADF, lignin and moisture content increased when rye grass stem increased. There were positive relationships of shearing force with diameter, linear density, stem thickness, ADF, lignin and moisture content of rye grass stem (P＜0.05). In situ degradability of rye grass stem decreased with increasing shearing force, but the linear correlations were not significant (P＞0.05). 【Conclusion】 The results showed that the variance in stem shearing force of Alfalfa and rye grass are due to a combination of factors, including changes in chemical composition, morphological characteristics. DM and NDF degradability of alfalfa stem had negative relationships with shearing force. Shearing force could be used as an indicator of forage stem nutritive value. There were no negative relationships between shearing force and DM, NDF degradability of rye grass.