We previously generated a high-metabolizable energy (HME) perennial ryegrass (Lolium perenne) by genetically modifying the plant to increase the leaf lipid content. Although substantial progress has been made toward characterizing physiological changes of HME ryegrass, very limited information exists for feeding value and its suitability for adoption into the pastoral system. In this study, independent HME ryegrass lines with a range of elevated leaf lipid concentrations were analyzed for changes in fatty acids and possible associated changes in the broader nutritional profile, including the gross energy, which was found to increase by 6.8%. Because ryegrass is often ensiled and fermentation in the rumen leads to biohydrogenation of fatty acids as well as enteric methane production, we sought to investigate these effects on HME ryegrass. This was achieved by performing mini-scale silos and using an automated gas measurement system to incubate the material in rumen fluid in vitro for 24 h. Our study included treatments comprising 3 independent HME ryegrass genotypes and wild-type control materials prepared fresh and as silage, employing in total 5 incubation studies, using rumen fluids collected from 4 nonlactating Jersey × Holstein cows. At intervals during the incubation, the production of gases, volatile fatty acids, and the degree of biohydrogenation were measured. Statistical data analysis indicated that differences in the nutritional compositions of the ensiled materials largely reflected those of their fresh counterparts. Incubation of both fresh and ensiled HME ryegrass in rumen fluid resulted in: (1) a greater percentage of valuable unsaturated fatty acids compared with the control; (2) a significant reduction of butyrate; and (3) a 10 to 15% decrease in the methane proportion of the total gas production. We conclude that ensiling could be a convenient option for preserving HME as a locally produced high-value supplementary feed; however, large-scale application needs to be investigated. In this paper we discuss the potential use of HME ryegrass to enhancing forage feeding value and the potential environmental benefits to the pastoral agriculture industry.

中文翻译：

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新鲜和青贮的转基因高代谢能量黑麦草的体外产气量和瘤胃发酵曲线。

我们之前通过对植物进行基因修饰以增加其叶脂含量而产生了高代谢能（HME）多年生黑麦草（Lolium perenne）。尽管在表征HME黑麦草的生理变化方面已经取得了实质性进展，但是关于饲喂价值及其适用于牧草系统的信息仍然非常有限。在这项研究中，分析了具有一定范围的叶脂浓度升高的独立HME黑麦草品系的脂肪酸变化以及包括总能量在内的更广泛的营养状况的可能相关变化，发现总能量增加了6.8％。由于黑麦草经常被青贮，瘤胃中的发酵会导致脂肪酸的生物氢化以及产生肠甲烷，因此我们试图研究这些对HME黑麦草的影响。这是通过执行小型料仓并使用自动气体测量系统在瘤胃液中将材料在体外孵育24小时来实现的。我们的研究包括使用3种独立的HME黑麦草基因型和新鲜和青贮饲料制备的野生型对照材料进行的处理，总共使用了5个孵化研究，使用了从4株非泌乳泽西岛×荷斯坦奶牛收集的瘤胃液。在温育期间的间隔时间，测量气体，挥发性脂肪酸的产生以及生物氢化的程度。统计数据分析表明，青贮材料的营养成分差异在很大程度上反映了其新鲜食材的营养成分。将新鲜和青贮的HME黑麦草在瘤胃液中孵育会导致：（1）与对照相比，有价值的不饱和脂肪酸比例更高；（2）丁酸酯的大量减少；（3）天然气总产量中甲烷比例减少10％至15％。我们得出的结论是，保鲜可能是将HME保留为本地生产的高价值补充饲料的便捷选择。但是，大规模应用需要进行研究。在本文中，我们讨论了使用HME黑麦草提高牧草饲料价值的潜在用途以及对牧业农业的潜在环境利益。大规模应用需要进行调查。在本文中，我们讨论了使用HME黑麦草提高牧草饲料价值的潜在用途以及对牧业农业的潜在环境利益。大规模应用需要进行调查。在本文中，我们讨论了使用HME黑麦草提高牧草饲喂价值的潜在用途以及对牧业农业的潜在环境利益。