Influence of substrate and aerobic exposure on chemical composition and the metabolome of silages and on the preference behavior of ruminants

• Applicant: Professor Dr. Karl-Heinz Südekum, since 2/2021
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437410805

Silage has become the most important feedstuff in rations for dairy cows and other ruminants worldwide. During feed-out aerobic degradation processes and heating of the silage can take place, accompanied by a decrease in feed quality and reduced acceptance by ruminants. In this time, several volatile organic compounds (VOC) are emitting, which can impact the air quality negatively and can contribute to ozone formation in the troposphere. Also with regard to feed intake VOC play an important role by influencing the sensory characteristics of the silage or the post-ingestive feedback received by the animal after ingestion. The composition of the VOC is changing continuously during aerobic exposure, as a consequence of microbial activity or volatilization. However, there is a lack of knowledge how their composition is changing and by which specific VOC the feed acceptance of ruminants is influenced such that explanations for the observed reduction in feed intake are still missing. For the first time in this extend, the planned research project will use metabolome analyses of the silages in addition to an extensive chemical characterisation and preference trials. The use of metabolomics can help to obtain a more detailed description of the chemical and molecular components of silages than before, as influenced by substrate, ensiling and aerobic exposure. Whole-crop silages of maize, lucerne and Italian ryegrass will be used in four replicates and compared in the three states “pre-ensiled”, “ensiled fresh” and “ensiled re-heated” (>3 K above ambient temperature). The aim is to get a overview about the complete silage composition and links to compounds that have not been detected and studied before but that possibly impact the feed choice behaviour. Compounds that change significantly in concentration during aerobic exposure will afterwards be added as pure substance in preference trials with goats and dairy cows to study their effect on forage choice and feed acceptance. For the first time in this extend we will be able to give an overview about substances that are linked to the aerobic deterioration of forages and to evaluate their effect on the feed acceptance of ruminants.

• DFG Programme: Research Grants
• Ehemalige Antragstellerin: Dr. Katrin Gerlach, until 1/2021