Multi-sensor measurement of O2, CO2 and reheating in triticale silage: An extended approach from aerobic stability to aerobic microbial respiration

Abstract

The biochemical reactions of aerobic microbial respiration (AMR) suggest that silage temperature (Tsi) rise, oxygen (O2) consumption and carbon dioxide (CO2) emission may be equally useful as indicators of silage deterioration during feed-out, but only temperature has been used extensively to assess aerobic stability. Here we extend the study of aerobic stability to incorporate AMR of silage by developing a novel experimental cell integrated with multiple sensors. Silage samples, ensiled from a triticale crop, were made in twelve air-tight barrels (60 L), packed to bulk densities of 190 or 250 kg m−3 dry matter (DM). Tsi and O2 measurements were co-located at 15- and 30-cm behind the working face. CO2 was measured as flux across the working face. The experimental period of aerobic exposure was 7 days. We provide the first reports of: (i) distinct aerobic responses of these parameters, showing that Tsi varied with CO2 in phase but with O2 out-of phase; (ii) CO2 flux was dominated initially by anaerobic discharge and subsequently by aerobic products; (iii) linear relationships between aerobic reheating and both O2 consumption (0.994 ≥ R2 ≥ 0.815, P < 0.01) and CO2 flux (0.981 ≥ R2 ≥ 0.464, P < 0.01); and (iv) variable magnitude of daily aerobic production of CO2 per kg DM from 2.3 to 133.4 mmol kg d−1. These results demonstrate that the novel multi-sensor technique has powerful capacity to provide insight into AMR of silage and thus provide more detailed information to guide silage management than previous measurements of aerobic stability.