An automated experimental system for tracking multiple factors of aerobic deterioration in silage: A mechatronic approach to a hybrid problem

Aerobic deterioration and resulting losses in silage are of worldwide concern to livestock managers. To mitigate degeneration of silage quality during feed-out, diverse chemical and biological additives have been developed. To allow efficient assessment of these additives, integrated chemical, microbiological and technological approaches are required but current methods are inadequate. Here we present an innovative mechatronic solution, combining robotic electronic gas detection (e-nose) of the fluxes of carbon dioxide (CO 2 ) and ethanol (EtOH) with in situ measurements of oxygen (O 2 ) concentration, pH and substrate temperature (T si ). Nine sample chambers allow complex experimental design. The efficacy of the multi-sensor-based system, by documenting the oxidative degradation of maize silage (four control samples and four treated with a Lactobacillus bio-additive), demonstrated: (i) O 2 is shown to be a potential indicator of microbial activity, initially stable at 18∼20 vol% then declining to 6.1∼12.5 vol%; (ii) T si and CO 2 exhibited similar dynamics, in opposite sense, rising with the decline of O 2 ; (iii) pH increased but lagged the decline of O 2 , and (iv) EtOH efflux increased only after O 2 was substantially depleted to 5.8∼13.4 vol%. The positive effect of the additive has been observed from all parameters measured in situ. This automated measurement system provides a new technique and experimental method to facilitate silage research and gas-emission investigations related to silage production.