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

青贮饲料既是一种重要的牲畜饲料，也是世界范围内沼气生产的主要底物，但极易发生好氧变质。腐坏的发生可以从青贮温度（Tsi）、pH和CO2流出量的测量中感知。然而，基本的解释和减轻损失的能力取决于对微生物学、植物成分和生物化学、物理化学和物理之间复杂相互作用的理解。拟进行的研究：(i)通过确定三种青贮作物（玉米、黑麦草、苜蓿）在酸化（发酵）和脱酸化（饲喂）阶段缓冲能力的滞后回路，考虑缓冲能力对青贮生产过程的双向影响；㈡根据菲克第一定律和第二定律，发展一种新的测量方法，用于在农场筒仓尺度上就地监测二氧化碳流出；（iii）在一系列实验条件下对Tsi、pH和CO2外排进行现场跟踪，以验证/改进用于预测青贮有氧变质的数学模型（Courtin-Spoelstra模型）；（iv）建立定量关系，使Tsi、pH和CO2外排可以作为青贮乳酸氧化分解过程中有氧变质的指标。在结合我们最近在青贮中发现的大量酸缓冲能力后，对每个实验中Flieg点法的评估将允许评估这种青贮质量测量的效用。

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.