摘要
The aim of this study was to quantify the variation in fatty acid (FA) content and composition in grass and maize silages and to identify key management factors during plant growth and the ensiling process that cause this variation. Samples of grass (n = 101) and maize (n = 96) silages were randomly collected from commercial dairy farms in The Netherlands in 2007 and 2008. Multivariate analysis was computed on data related to agronomic conditions, harvest-maturity, wilting management (grass only), chemical composition and feeding value of the individual silages to search for variables which cause the variation in FA contents. Total FA content was highly variable in grass (8.10�32.47 g/kg DM) and maize (12.37�35.25 g/kg DM) silages, and contents of all major individual FA also had a high variation. The content of C18:3n-3 had large variation (3.57�20.53 g/kg DM) in grass silages, while C18:2n-6 had large variation (6.89�22.41 g/kg DM) in maize silages. Redundancy analysis (i.e., a combination of principal components analysis and multiple regression) showed that variables related to plant maturity at harvest explained most of the variation in FA content, with silages from young grass and young maize having high contents of C18:3n-3. Plant cell wall components and digestibility are related to the maturity at harvest and were strong predictors of the FA contents in grass and maize silages. Regression equations based on nutrient composition provided relatively good estimations of the contents of C18:3n-3 (R2 = 0.73) and total FA (R2 = 0.65) in grass silages. Regression equations based on nutrient composition and feeding values gave relatively good estimations of the contents of C18:2n-6 (R2 = 0.51) and total FA (R2 = 0.48) in maize silages. Bruising (i.e., removing of the waxy layer of leaves and stem), silage pH and ammonia content did not affect the FA content in the grass silages.
摘要译文
antify脂肪酸（FA）的含量和组成的草和青贮玉米的变化和植物生长和青贮过程中造成这种变化中找出密钥管理的因素。草样品（n \x3d 101）和玉米（N \x3d 96），青贮饲料，随机从荷兰商业奶牛场在2007年和2008年采集的。多因素分析，计算上与农艺条件的数据，采收成熟度，萎蔫管理（仅限草）化学成分和各青贮馈送值来搜索变量引起在FA含量的变化。总FA含量在草丛中高度可变（8.10鈥47 g/kg DM) and maize (12.37鈥53克/千克DM）草青贮，而C18：2N-6有大的变化（6.89鈥主成分分析和多元回归）的组合表明，在收获种植的成熟相关的变量解释最FA含量的变化，具有C18含量高的嫩草和年轻的玉米青贮：3N-3。植物细胞壁的成分和消化率都涉及到成熟收获，并分别在草和青贮玉米的FA内容强烈的预测。根据所提供的C18的内容比较好的估计营养成分回归方程：3N-3（R SUP 2 / SUP \x3d 0.73）和总FA（R SUP 2 / SUP \x3d 0.65），在草丛中青贮。根据营养成分和饲用价值回归方程给了C18的内容比较好的估计：2N-6（R SUP 2 / SUP \x3d 0.51）和总FA（R SUP 2 / SUP \x3d 0 。48）在玉米青贮。青紫（即去掉叶子和茎的蜡质层），青贮pH值和氨鈥揘内容并没有影响在草青贮足总杯内容。
N.A. Khan; J.W. Cone; V. Fievez; W.H. Hendriks. Causes of variation in fatty acid content and composition in grass and maize silages.[J]. Animal Feed Science and Technology, 2012,174(1-2): 36-45