Precise characterization of aerobic deterioration of silage associated with pH, reheating, CO2 efflux, lactic-acid loss and effect of buffering capacity

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Silage is both a critical livestock feed and a major substrate of biogas production worldwide, but is greatly prone to aerobic deterioration. The occurrence of spoilage can be perceived from measurements of silage temperature (Tsi), pH and CO2 efflux. However, the fundamental interpretation and ability to mitigate losses, depends on understanding the complicated interactions among microbiology, plant composition and biochemistry, physical chemistry and physics. The proposed study: (i) Considers the bidirectional effect of buffering capacity on the silage making process by determining the hysteresis loop of the buffer capacity of three silage crops (maize, ryegrass, alfalfa) along the acidification (fermentation) and de-acidification (feed-out) phases; (ii) Develops a novel measurement method for in situ monitoring of CO2 efflux at the farm silo scale based on the Fick’s first and second laws; (iii) Employs in situ tracking of Tsi, pH and CO2 efflux under a range of experimental conditions, to validate/improve a mathematical model (Courtin-Spoelstra model) that was developed for predicting aerobic deterioration in silage; (iv) Develops quantitative relationships to allow Tsi, pH and CO2 efflux to serve as indicators of aerobic deterioration during oxidative decomposition of lactic acid in silage. Evaluation of the Flieg’s point method in each experiment will allow assessment of the utility of this measure of silage quality after incorporating our recent discovery of substantial acid buffering capacity in silage.