TABLE 1.
Dissolved dihydrogen concentration in the rumen.
| References | Treatment or condition | Method of measurement | H2 (μM)1 |
| Hungate (1967) | Non-inhibited methanogenesis | H2 extraction procedure | 0.19–30.4 |
| Robinson et al. (1981) | Non-inhibited methanogenesis | H2 extraction procedure | 2–15 |
| Hillman et al. (1985) | Non-inhibited methanogenesis | Mass spectrometry | 0.6–5.8 |
| Smolenski and Robinson (1988) | Non-inhibited methanogenesis | H2 sensor | 0.36–20.1 |
| Guyader et al. (2015) | Non-inhibited methanogenesis | H2 sensor | 3.58 |
| Nitrate | 45.3 | ||
| Linseed | 4.03 | ||
| Nitrate + linseed | 21 | ||
| Wang et al. (2016) | Oat grass | H2 extraction procedure | 6.49 |
| Barley straw | 2.34 | ||
| Wang et al. (2017) | Control | H2 extraction procedure | 1.02 |
| H2 released with Mg | 1.99 | ||
| Wang et al. (2018) | Control | H2 extraction procedure | 2.37 |
| Nitrate | 4.79 | ||
| Ma et al. (2019) | Control | H2 extraction procedure | 1.76 |
| H2 released with Mg | 2.68 | ||
| Melgar et al. (2019) | Control | Gas-stripping | 7.3 |
| Methanogenesis inhibited with 3-nitrooxypropanol | 43.6 |
1Greater ranges in H2 concentration in some studies in which methanogenesis was not inhibited are due to multiple measurements throughout the day in animals fed once or twice a day, rather than to variation caused by treatments imposed.