The increase in the intensity of ruminant production determines changes in the rumen feed conversion and thus, among other, may increase pool of greenhouse gases emission. The ineffective digestion process and changes in the legislation processes implicate the action tends towards the limitation of rumen ammonia and methane production. In the last few years there is an increasing interest of nutritionists in bioactive plant factors – phytofactors as natural feed additives that can modify the rumen fermentation processes, improve the protein metabolism and, at the same time, reduce ammonia production and emission, and curb methane production and emission to the atmosphere. High diversity of bioactive phytofactors contained in many plant species has been identified as a potential factor affecting the above-mentioned processes.