Ruminants can digest fiber with a special stomach: the rumen. The host do not have the ability to achieve that, while the inhibitors including bacteria, fungi and protozoa within the rumen can do that in a series aerobic processes called fermentation.

Unfortunately, methane is also generated by a microbe called methanogens along with degrading of feed. Methane emission from ruminant is the second artificial factor to global greenhouse effect.

Before interfering the methanogenesis processing, scientists need to understand what happens in the rumen. The rumen is composed of several muscular sacs including the cranial sac in the front, ventral sac in the middle and ventral blind sac in the rear.

Researchers in the Institute of Subtropical Agriculture (ISA) of the Chinese Academy of Sciences investigated 3 ruminally-cannulated non-lactating Chinese Holstein dairy cows fed a 40% forage and 60% concentrate feeds diet. The samples from three different parts of the rumen was investigated.

"We know that the dissolved methane is higher in the front rumen from our former research," said MA ZhiYuan, a doctoral researcher at ISA. "However, we are not sure what makes that happen. Is the methane generated faster in the front rumen than the other parts? If so, why?"

The front rumen is a special sac separated by muscular pillar from the rest of the rumen and connected to the esophagus with an orifice. Does the incoming saliva from the esophagus change the rate of methane formation in the front rumen since the pH is a crucial factor that influence microbes including the methanogens?

They found pH and population of the Methanobrevibacter, the dominant methanogen order was highest in samples from the front rumen, which confirmed their hypothesis. And this is the first report to state the formation of methane by methanogens in the rumen is uneven.

This work was supported by the National Natural Science Foundation of China, National key research and development program of China, China Agriculture Research System and CAS President’s International Fellowship for Visiting Scientists.

The study entitled "Short communication: Variability in fermentation end-products and Methanogen communities in different rumen sites of dairy cows" was published in Journal of Dairy Science.

Contact: WANG Min

E-mail: mwang@isa.ac.cn