A small scale in vitro system for high throughput gas production analysis – A comparison with the Hohenheim gas test

Abstract

An automated small scale in vitro system has been developed for the extensive examination of feedstuffs in high throughput screenings. This system was calibrated against the strictly standardized Hohenheim gas test (HGT). The automated system is suitable for gas-producing biological suspensions, e.g. ruminal fluid. Gas production is indirectly measured through pressure increase as a measure for digestibility. For functional characterisation of the micro gas system (MGS), a total number of 18 feedstuffs, including grass hay and a concentrate standard, were simultaneously incubated in the HGT and the MGS. The same inoculate and feed-inoculate ratio was applied for comparisons of kinetic parameters. Compared to HGT, the MGS resulted in significantly lower (p < 0.05) maximum gas production for all feedstuffs. Regarding the rate of gas production, the lag phase using the MGS was longer compared to HGT for 12 feeds. However, a strong relationship between the HGT and MGS gas production after 24 h was observed. The regression analysis of feedstuff mean values of both methods resulted in the equation: y = 0.91 (SE = 0.0342; p < 0.0001) x -0.03 (SE = 1.3924; p = 0.9823) with R² = 0.98. The results indicate that the MGS is a suitable alternative method for high throughput screenings but also, with reservations, for questions which were formerly examined with the HGT.