Hartinger, Thomas Dietmar Said: Effects of pre-ensiling treatments on quality of lucerne silages, in vitro rumen fermentation and microbiota composition. - Bonn, 2019. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-56826
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-56826,
author = {{Thomas Dietmar Said Hartinger}},
title = {Effects of pre-ensiling treatments on quality of lucerne silages, in vitro rumen fermentation and microbiota composition},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2019,
month = dec,

note = {Lucerne (Medicago sativa L.) silages (LS) are commonly fed to ruminants. Due to substantial proteolysis during ensiling, the majority of crude protein (CP) in LS is non-protein nitrogen (NPN), which is rapidly degraded to ammonia in the rumen and to a great extent ultimately lost in urine, meaning increased environmental pollution. Post-harvest conditions strongly affect LS properties, notably the CP fraction by decelerating proteolysis, hence resulting in silages with less NPN and finally a potentially increased ruminal N utilization from LS. Therefore, the present thesis investigated the effects of the pre-ensiling treatments dry matter (DM) concentration, wilting intensity and sucrose addition on LS quality, in vitro rumen fermentation and microbiota composition. The first article of this thesis provides a detailed literature review on major nitrogenous compound-degrading rumen microbes and options to manipulate their activity and abundance in the rumen. The next study measured the effects of the aforementioned pre-ensiling treatments on LS quality with the novel aspect of wilting intensity, which has not been considered so far for lucerne ensiling. All three pre-ensiling treatments reduced the NPN concentration in the LS and combining high-intensity wilting to 35% DM concentration with sucrose addition resulted in highest true protein preservation, in which sucrose addition further enhanced lactic acid fermentation. The subsequent article presents the rumen fermentation characteristics during LS incubation in a long-term in vitro rumen simulation system. A higher DM concentration and the addition of sucrose increased the concentration of total volatile fatty acids and gas production, but reduced fibre degradability. High-intensity wilting increased hemicellulose degradability but decreased the degradability of organic matter, whereas most variables of ruminal N utilization were less affected. The last study focuses on how the pre-ensiling treatments affected the microbiota composition in the rumen simulation system. Sucrose addition was the main driver for alterations in the microbial community, but also adaption time of the microbes to the LS clearly shaped the composition. Overall, this study demonstrates that pre-ensiling treatments can substantially support a sufficient fermentation and true protein preservation of LS during ensiling. Although these beneficial effects were not completely rediscovered during in vitro rumen fermentation, promising results on fibre degradability encourage further investigations. The microbiological analysis revealed first insights on how the pre-ensiling treatments affect the ruminal microbiota composition, which might help to understand alterations in the rumen fermentation. In conclusion, the applied pre-ensiling treatments improve the quality of LS and have potential to increase the ruminal N utilization from LS. Efforts in this direction should be pursued and refined in the future.},
url = {http://hdl.handle.net/20.500.11811/8027}

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