By Jamie Hawley, ASAS Communications Intern
June 20, 2016 – Ruminal gases include carbon dioxide, hydrogen, and methane. Hydrogen is an essential substrate for methanogens (methane-producing rumen bacteria) to produce methane, and also influences fermentation pathways in the rumen. Dissolved hydrogen is the form of hydrogen available to rumen bacteria.
Little is known about how sampling techniques, including oral stomach tubing with different insertion depths and sampling from different rumen sites through a cannula (see image), affect the measurement of ruminal dissolved hydrogen.
Min Wang and colleagues at the Institute of Subtropical Agriculture, Chinese Academy of Sciences and AgResearch, have found that oral stomach tubing may be a feasible method to collect ruminal dissolved hydrogen in intact animals.
Rumen fluid samples collected though rumen cannula and oral stomach tubing from 4 dairy cows were compared for dissolved hydrogen. Rumen fluid was collected at 0, 2.5, and 6 hours after morning feeding through the cannula from cranial dorsal rumen, cranial ventral rumen, central rumen, caudal dorsal rumen, and caudal ventral rumen and by oral stomach tubing at 2 insertion depths of 180 cm (sampling the central rumen) and 200 cm (sampling the caudal dorsal rumen).
Rumen fluid collected by oral stomach tubing contained dissolved hydrogen concentrations similar to that collected through the rumen cannula. Dissolved hydrogen concentrations in the rumen fluid collected through oral stomach tubing at insertion depths of 180 and 200 cm were similar to those collected through the central rumen and caudal dorsal rumen sites, respectively.
While oral stomach tubing may prove to be a feasible method for measuring ruminal dissolved hydrogen in intact animals, the authors caution that care must be taken to minimize saliva contamination.
Read more about this research in the Journal of Animal Science: Just Published. The article is open access.