Emissions of volatile fractions from tropical silages: Strategies to mitigate the nutrient losses and environmental pollution

Abstract

Silages make up most of the conserved forages used in beef and dairy herds in Brazil. During the fermentation, microbial growth leads to volatile organic compounds (VOC) formation. These products have substantial importance on animal nutrition. However, during silage feedout, VOC and other gases may evaporate and lead to nutrient losses and environmental pollution. The objective of this project will be: 1) identify VOC formed during the fermentation of tropical silage; 2) estimate rates of gases emission from silages; and 3) suggest strategies to mitigate emissions, resulting in less nutrient losses and environmental pollution. At the first phase of this research, it will be determined the occurrence of novel fermentation end-products in tropical silages (maize, sorghum, tropical grasses, sugarcane, high moisture corn), by gas chromatography-mass spectrometry. Qualification of VOC emissions will be performed by the headspace technique. In the phase 2, some strategies will be tested to mitigate the gases emission during fermentation and aerobic exposure of silages. Energy losses, potential pollution, and global warming potential will be calculated. In the phase 3, the most promising mitigation strategies recognized at the 2nd phase, will be evaluated both in farm-scale silos and total mixed rations containing those silages. In the last step, the kinetic of gas production from ruminal fermentation will be performed in vitro. Thus, the energy losses and environmental pollution potentials will be determined over the whole process of conservation and utilization of tropical silages.