A ring test of a wireless in vitro gas production system

Abstract

The in vitro gas production (GP) technique has been widely used for feed evaluation. However, variability in results limits useful comparisons. Results from a ring test undertaken in four laboratories (Italy – IT, Spain – SP, Wales – WA and Denmark – DK) using the same wireless equipment (ANKOM Technology), same substrates and same laboratory protocol are presented, including calculation of repeatability and reproducibility according to ISO 5725-2. Hay, maize starch and straw samples and units without sample (blanks) were incubated in five repetitions using rumen inoculum from cows (DK, IT and WA) or sheep (SP). Curves, corrected for blanks, were fitted using an exponential regression model with a lag time. The following variables were considered: (i) GP24 and GP48: raw values at 24 and 48 h (mL/g DM), corrected for blanks; (ii) A: asymptotic GP (mL/g DM); (iii) T1/2: time when half A is produced (h); (iv) GPMR: maximum predicted GP rate (mL/h); (v) L: lag time (h). A mixed model including laboratories as random effect was used. A significant interaction between substrate and laboratories was found for all variables except A. The most repeatable and reproducible results were observed for A and GP48. The results from this ring test suggest the need for more standardisation, particularly in the procedures that occur outside the laboratory.

In vitro–in vivo study on the effects of plant compounds on rumen fermentation, microbial abundances and methane emissions in goats

“…Doses were 0, 40, 80, 160 and 320 µl/l, with the exception of BCM that was added at 160 and 320 µl/l doses. A commercial wireless system (Ankom RF Gas Production, Ankom Technology, NY, USA) consisting of bottles equipped with pressure sensor modules and a reception base station connected to a computer was used to measure pressure as described by Cornou et al (2013). After 24 h of incubation, the fermentation was stopped by placing the bottles in ice and the content filtered to collect a sub-sample: 0.8 ml for VFA analysis was collected and was kept at −20°C.…”

“…The volume of gas produced in Experiment 1 was calculated from the readings of gas pressure in the 24 h of fermentation as described by Cornou et al (2013). The gas produced in batch cultures (Experiment 2) was adjusted to the model: et al, 2000), where y represents the cumulative gas production (ml); t represents the incubation time (h); A represents the asymptote (potential gas volume at steady state; ml); and c represents the gas production rate (h − 1 ).…”

Design, implementation and interpretation of in vitro batch culture experiments to assess enteric methane mitigation in ruminants—a review

“…The main difference with previous automated systems (Cornou et al, 2013) is that fermentation gases are collected and analysed by a computer-controlled gas chromatograph, rather than being released into the air once a threshold pressure is reached.…”

“…CH 4 ) typically requires manual injection of sample gases into a gas analyzer (Martínez et al, 2010;Pellikaan et al, 2011). Cornou et al (2013) described the results of a ring-test evaluating the use of a wireless system for automated gas release developed by Ankom (Ankom Technology, Macedon, NY, USA). This system is being used in various laboratories, but still relies on manual gas sampling and analysis.…”

“…1000 Yes n.s. Cornou et al (2013) Yes Automated GC GC, gas chromatograph; n.s., not specified. Wilkins (1974) described a different approach to measure fermentation kinetics in vitro, whereby fermentation took place in a sealed vessel containing rumen fluid, buffer and substrate, and a pressure transducer was used to measure gas accumulation in the vessel headspace.…”