Using canonical correlation analysis to understand the rumen biohydrogenation patterns of linoleic and alpha-linolenic acids in the rumen fluid of bovines

ABSTRACT. The objective of this study was to determine the multivariate relationship among linoleic acid, alpha-linolenic acid, and their main rumen biohydrogenation (BH) intermediates and products in bovine rumen fluid using canonical correlation analysis (CCA). A dataset consisting of 1177 observations generated by 107 in vitro rumen incubation systems of pure and mixed linoleic acid (18:2-c9, c12) and alpha-linolenic acid (18:3-c9, c12, c15) was gathered. Two canonical variates were defined: A: composed of the nine main BH intermediates and products (18:2-c9, t11; 18:2-t11, c15; 18:1-t11; 18:1-t9; 18:1-t6; 18:1-c11; 18:1-c6; 18:1-c9; 18:0) of 18:2-c9, c12 and 18:3-c9, c12, c15 and B: composed of 18:2-c9, c12 and 18:3-c9, c12, c15. Two canonical functions between A and B with significant canonical correlations (R1=0.990 and R2=0.738; p <0.01) were obtained. However, only the first function was selected for CCA. Exploration of canonical loadings for first function, revealed the following quantitative significance (absolute value) order for fatty acids (FA) within their respective canonical variates: A: 18:0(0.958)>18:1-t9(0.837)>18:1-c11(0.835)>18:1-c6(0.824)>18:1-t11(0.747)>18:1-c9(0.738)>18:1-t6(0.415)>18:2-t11, c15(0.387)> 18:2-c9, t11(0.239); B: 18:2-c9, c12(0.667)>18:3-c9, c12, c15(0.488). The CCA showed that 18:2-c9, c12 has a greater contribution than that of 18:3-c9, c12, c15 on the production of the aforementioned BH intermediates, in which 18:0, as well as the groups of 18:1 cis and trans-FA were mainly affected.

摘要。本研究旨在通过典型相关分析（canonical correlation analysis, CCA），阐明牛瘤胃液中亚油酸（linoleic acid）、α-亚麻酸（alpha-linolenic acid）及其主要瘤胃生物氢化（rumen biohydrogenation, BH）中间产物与终产物之间的多元关联。本数据集包含107组纯品或混合态亚油酸（18:2-c9,c12）与α-亚麻酸（18:3-c9,c12,c15）的体外瘤胃培养体系所生成的1177条观测数据。本研究定义了两组典型变量：变量A由亚油酸（18:2-c9,c12）与α-亚麻酸（18:3-c9,c12,c15）的9种主要瘤胃生物氢化中间产物与终产物构成，具体包括18:2-c9,t11、18:2-t11,c15、18:1-t11、18:1-t9、18:1-t6、18:1-c11、18:1-c6、18:1-c9、18:0；变量B则由亚油酸（18:2-c9,c12）与α-亚麻酸（18:3-c9,c12,c15）构成。最终得到变量A与B之间的两组典型相关函数，其典型相关系数分别为R₁=0.990与R₂=0.738（均p<0.01），具有统计学显著性。但本研究仅选取第一组典型函数用于后续典型相关分析。对第一组典型函数的典型载荷进行探索后发现，两类典型变量内部各脂肪酸（fatty acids, FA）按其载荷绝对值的定量重要性排序如下：变量A：18:0(0.958)＞18:1-t9(0.837)＞18:1-c11(0.835)＞18:1-c6(0.824)＞18:1-t11(0.747)＞18:1-c9(0.738)＞18:1-t6(0.415)＞18:2-t11,c15(0.387)＞18:2-c9,t11(0.239)；变量B：18:2-c9,c12(0.667)＞18:3-c9,c12,c15(0.488)。典型相关分析结果显示，亚油酸（18:2-c9,c12）对上述瘤胃生物氢化中间产物生成的贡献度高于α-亚麻酸（18:3-c9,c12,c15），其中18:0以及顺式、反式单不饱和脂肪酸类群为主要受影响对象。