Rumen cannulation is a widely employed technique in ruminant nutrition research. However, the gap between skin and rumen cannula can cause leakage of fermentation gases and influx of atmospheric air, which may adversely affect the anaerobic environment in the rumen.

Researchers from China Agricultural University and the Institute of Subtropical Agriculture (ISA) of the Chinese Academy of Sciences investigated the effects of rumen cannulation on ruminal dissolved gases and methanogenesis. Their findings were published in Journal of Dairy Science.

Scientists found that rumen cannulation decreased headspace gaseous hydrogen (gH₂) and gaseous methane (gCH₄) concentration in the gas phase of rumen. Both dissolved hydrogen (dH₂) and dissolved methane (dCH₄) had saturation factor larger than 1, which indicated super-saturation.

Rumen cannulation increased the concentration of dCH₄ and the saturation factor of dCH₄. However, rumen cannulation did not alter dH₂ concentration, but increased saturation factor of dH₂.

Although cannulation increased super-saturation of dH₂ and dCH₄, it decreased dCO₂ concentration in the liquid phase of rumen. The decreased dCO₂ may be caused by the leakage of headspace CO₂ from the rumen.

Rumen cannulation did not alter molar percentage of major individual volatile fatty acid (VFA), except valerate. This slight change in VFA profile did not alter estimated metabolic hydrogen production relative to the amount of total VFA produced, and thus was not the main cause of increased dCH₄ concentration in this study.

Rumen cannulation led to an increase in 16S rRNA copies specific to methanogens even though dCO₂ decreased in response to cannulation. This contradiction can be caused by the increased saturation factor of dCH₄ in cannulated cows.

Moreover, rumen cannulation altered methanogen community structure, with increased methanogen population but reduced abundance of Methanosphaera.

The research was supported by National Key Research and Development Program of China, National Natural Science Foundation of China, State Key Laboratory of Animal Nutrition, Hunan Province Science and Technology Plan, China Agriculture Research System, Youth Innovation Promotion Association of Chinese Academy of Sciences, CAS President’s International

Contact: Wang Min

E-mail: mwang@isa.ac.cn

Institute of Subtropical Agriculture, Chinese Academy of Sciences