Studies on quantitative and qualitative effects of lucerne silages with varying nitrogen fractions on ruminal nitrogen metabolism and the ruminal bacterial population

在反刍动物营养中，苜蓿青贮饲料是一种具有相当生态和营养潜力的饲料。然而，在青贮之前，植物材料中已经发生了广泛的代谢反应，这可能受到萎蔫条件的很大影响，并可能对粗蛋白质组成产生重大影响，从而对青贮饲料的蛋白质质量产生重大影响。在草青贮的情况下，不同的萎蔫条件一方面导致青贮的真蛋白质百分比很高，而在其他青贮中，在萎蔫过程中粗蛋白质的降解继续推进，导致非蛋白质n的百分比很高。我们假设在苜蓿青贮中也有类似的过程，并且它们在很大程度上影响了青贮的质量。由于瘤胃氮和碳水化合物代谢的相互依赖性，可以假设氮组分的不同组成导致了瘤胃代谢的广泛改变。所提交项目的基础是根据不同的萎蔫条件生产不同组成N组分的苜蓿青贮。在对这些青贮物进行广泛的化学表征后，将通过半连续长时间瘤胃模拟系统研究其对瘤胃氮和碳水化合物代谢的影响。由于不同的底物供应，可以假设在瘤胃微生物种群中将观察到变化，并且将采取特定的样品通过分子遗传学方法跟踪这些变化。特别是游离氨基酸含量较高的青贮品种，可能会促进氨基酸发酵菌的生长，导致氮周转增加，同时降低瘤胃微生物粗蛋白质的合成效率。该项目的研究结果将为青贮饲料的生产提供重要的知识。在萎蔫过程中，苜蓿青贮的后期品质就会受到有意的影响。由此可以生产出保证瘤胃微生物粗蛋白质高效合成的苜蓿青贮饲料。

In ruminant nutrition lucerne silage is a forage with considerable ecological and nutritional potential. However, already prior to ensiling are extensive metabolic reactions in the plant material occur, which may be considerably affected by wilting conditions and may have a significant influence on crude protein composition and, thus, protein quality of the silage produced. In the case of grass silages differing wilting conditions lead to silages with a high percentage of true protein on the one hand whereas, the degradation of crude protein during wilting continues to advance in other silages and leads to high percentages of non-protein N. We assume that there are similar processes in lucerne silage and that they influence the quality of the silages considerably. Because of the mutual dependence of ruminal N and carbohydrate metabolism it can be hypothesized that the differing composition of N fractions leads to extensive alterations in ruminal metabolism. The basis of the submitted project is production of lucerne silages with differently composed N fractions due to different wilting conditions. After an extensive chemical characterization of these silages, their effects on ruminal N as well as carbohydrate metabolism will be studied by means of a semi-continuous long-time rumen simulation system. Because of the differing substrate supply it can be assumed that shifts will be observed in the ruminal microbial population and there will be specific samples taken to track these changes by molecular genetic methods. Especially silage varieties with high percentages of free amino acids might facilitate growth of amino acid-fermenting species leading to an increase of N turnover accompanied by less efficient rumen microbial crude protein synthesis. The results of this project will significantly contribute to the knowledge of silage making. Already during wilting the later quality of lucerne silages could be purposefully influenced. With that lucerne silages that ensure efficient microbial crude protein synthesis in the rumen might be produced.