Essential oils are plant extracts that can enhance the palatability of dairy rations. These additives typically include compounds such as coriander seed oil, eugenol (from cloves), geranyl acetate and geraniol. By improving the sensory aspects of rations using these additives, feed intake, nutrient use efficiency and consequently cattle performance, can be improved.
For dairy farmers exploring feed ingredients to help reduce methane emissions and improve overall herd efficiency; research suggests that essential oils can also influence rumen function, leading to lower methane emissions.
Evidence suggests that essential oils can shift the microbial population in the rumen; therefore, influencing fermentation patterns linked to methane production. Some studies have observed reductions in methane output of 5–10 %, although results can vary depending on diet, system and inclusion rate.
Alongside potential emissions benefits, there is some evidence of performance gains from essential oil supplementation. For example, milk yield increases of around 4% have been reported in some research. But, as with any feed ingredient, outcomes will depend on how it fits within the wider dairy ration and herd management.
Liam Sinclair, Professor of Animal Science at Harper Adams University, said: “Essential oils are relatively easy to include in the diet of dairy cows as they are fed at a low level (e.g. 1 g/cow/day) and do not require changes to the diet. Essential oils can also be included in the [total mixed ration (TMR)], the concentrate or drinking water, and more recently are available as a slow-release bolus, making it easier to supplement grazing-only cattle.”
For farms involved in the UK Dairy Carbon Network, essential oils offer a simple, feed-based approach which could improve efficiency and reduce environmental impact. But, adding an ingredient such as essential oils will depend on a number of factors. The right choice will depend on their farm system, feeding approach and business priorities.
Our Farm Liaison Officers and technical support teams are supporting participating farms by discussing the available options and sharing the latest evidence to help them decide what could work best in their specific systems.