# Development and Validation of a Custom-Built System for Real-Time Monitoring of In Vitro Rumen Gas Fermentation

## TL;DR

Researchers created a low-cost system to monitor gas production in cow stomach fermentation, which works as well as an expensive commercial system.

## Contribution

A modular, low-cost gas monitoring system (FerME) was developed and validated as a cost-effective alternative to commercial systems.

## Key findings

- FerME performed similarly to the Ankom RF system in measuring gas production and fermentation parameters.
- Using filter bags reduced gas output and increased propionate concentrations.
- FerME had improved precision and was about half the cost of the commercial system.

## Abstract

We developed a low-cost and easy-to-build device to monitor gas production during fermentation, such as in cow stomachs. It performed similarly to a commercial system but gave more consistent results. We also found that encasing the feed in filter bags reduced gas production, likely due to limited microbial access. This tool provides an affordable and flexible option for fermentation studies in animal science and environmental research.

While the Ankom RF system facilitates efficient high-throughput in vitro fermentation studies, its high cost and limited flexibility constrain its broader applicability. To address these limitations, we developed and validated a low-cost, modular gas monitoring system (FerME), assembled from commercially available components. To evaluate its performance and reproducibility relative to the Ankom RF system (Ankom Technology, Macedon, NY, USA), in vitro rumen fermentation experiments were conducted under strictly controlled and identical conditions. Whole rumen contents were collected approximately 2 h post-feeding from individual mid- or late-lactation dairy cows and immediately transported to the laboratory. Each fermenter received 50 mL of processed rumen fluid, 100 mL of anaerobically prepared artificial saliva buffer, and 1.2 g of the donor cow’s diet. Bottles were sealed with the respective system’s pressure sensors, flushed with CO2, and incubated in a 50 L water bath maintained at 39 °C. FerME (New Taipei City, Taiwan) and Ankom RF fermenters were placed side-by-side to ensure uniform thermal conditions. To assess the effect of filter bag use, an additional trial employed Ankom F57 filter bags (Ankom Technology, Macedon, NY, USA; 25 μm pore size). Trial 1 revealed no significant differences in cumulative gas production, volatile fatty acids (VFAs), NH3-N, or pH between systems (p > 0.05). However, the use of filter bags reduced gas output and increased propionate concentrations (p < 0.05). Trial 2, which employed filter bags in both systems, confirmed comparable results, with the FerME system demonstrating improved precision (CV: 4.8% vs. 13.2%). Gas composition (CH4 + CO2: 76–82%) and fermentation parameters remained consistent across systems (p > 0.05). Importantly, with 12 pressure sensors, the total cost of FerME was about half that of the Ankom RF system. Collectively, these findings demonstrate that FerME is a reliable, low-cost alternative for real-time rumen fermentation monitoring and could be suitable for studies in animal nutrition, methane mitigation, and related applications.