Is rumen functioning modified when animals are reared under lower oxygen pressure conditions (high mountains)?

I would rather say that that the composition of vegetation (more herbs) plus an eventuual lack of energy can alter fatty acid compsition towards 18:3n-3. Also the amount of n-6 containing small grains and maize might lead to an elevated omega-3 content. The effect of herbs in the vegetation could alter rumen function but I think this is still quiet a black box. In this paper researcher saw a difference (http://www.publish.csiro.au/paper/AN12109.htm) with cows fed at different altidudes but I cannot see if this is again maybe due to vegetation or lack of energy in plants eaten.

Dear Norbert, Interesting comment. Thank you very much.

The rumen does not need oxygen so it is unlikely. Most likely effect is on slowed metabolism at cellular level which the animals acclimatise to over time.

Dear Prof. Mpofu, My question was focused on the second topic you mentioned: changed metabolism and its effects on rumen functioning. Thank you, Regards, Alferdo J. Escribano.