Leverage of Essential Oils on Faeces-Based Methane and Biogas Production in Dairy Cows

Currently, there is an ongoing intensive search for solutions that would effectively reduce greenhouse gas emissions (mainly methane) into the environment. From a practical point of view, it is important to reduce methane emissions from cows in such a way as to simultaneously trim emissions from the digestive system and increase its potential production from feces, which is intended as a substrate used in biogas plants. Such a solution would not only lower animal-based methane emissions but would also enable the production of fuel (in chemical form) with a high yield of methane from biogas, which would boost the economic benefits and reduce the use of fossil fuels. We tested the effect of administering an essential oil blend consisting of 5.5% oils and fats on methane and biogas production from dairy cow feces during fermentation. Three subsequent series (control and experimental) were conducted in dairy cows fed a total mixed ration (TMR) rich in brewer’s cereals and beet pulp, with 20% dry matter (DM) of the total diet. Cows from the experimental group received 20 g/cow/day of essential oil blend, namely a commercial additive (CA). The study showed that CA can increase the production of methane and biogas from dairy cow feces. It can be concluded that in the experimental groups, approx. 15.2% and 14.4% on a fresh matter basis and 11.7% and 10.9% on a dry matter basis more methane and biogas were generated compared to the control group, respectively. Therefore, it can be assumed that the use of CA in cow nutrition improved dietary digestibility, which increased the efficiency of the use of feces organic matter for biogas production.