A ruminant animal refers to a large group of herbivores with a four-chambered stomach, the largest of which is the rumen. Most ruminants have hooves with two digits, and they are also the only animals that can digest their food without thoroughly chewing it. Commonly known ruminant animals include cows, sheep, goats, moose, camels, deer, giraffes, and buffalos.
Methane occurs when microorganisms in the rumen of ruminants break down the feed into fatty acids. The amount of methane that is formed is affected by the feed intake, but there is also great variation between animals which can be explained by the feed state, genes and the microbial composition in the rumen.
Special feed additives can be used to reduce the formation of methane in feed digestion from ruminants. For example, an increased proportion of fat in the feed has a known methane-inhibiting effect as fatty acids do not ferment in the rumen.
A certain amount of fat in the feed in the form of, for example, rapeseed-based products has therefore been used for a long time, but too much fat in the feed can be negative for feed utilization and for the cows’ health. Development in the field has been rapid in recent years and there are today several new interesting additives with higher potential, where some have been introduced to the market and others are in an earlier development phase.
A feed additive, where the active substance is the chemical substance 3-nitrooxypropanol (3-NOP), has been fed to several different animal categories of cattle in a large number of trials in several countries including Sweden. The additive has been approved for use in dairy cows in conventional production systems within the EU since February 2022.
A daily feeding with the recommended amount of the additive in the feed can, according to one manufacturer, reduce methane emissions by an average of around 30% in dairy cows and by 45% in cattle for meat production. These values are based on a large number of scientific studies and field trials in several countries. Another additive that has shown potential to reduce methane is based on red algae, where the active substance is bromoform, but here considerably more knowledge is needed in terms of optimizing cultivation and use. According to one manufacturer, daily feeding with the product can reduce methane emissions by up to 90 percent in meat animals.
According to Swedish researchers in the field and ongoing industry work, it is these two products above all that are considered particularly relevant at the moment. Although the active substances are different, they act in a similar way to inhibit methane production.
In a Danish evaluation from 2023, in addition to the above-mentioned additives, nitrate was also examined. It was found that all have a methane-reducing effect, but that there are limits to how much can be added to the feed, as too high a concentration above all can affect the feed intake.
Although certain feed additives appear to have significant potential, there is still uncertainty about, above all, the long-term effects, and that there are other limitations to increasing use within different production systems. More research and analysis is required both with regard to products marketed today and to develop alternative, future feed additives. There is a lot of research and trial activity with various additives around the world. In Sweden, for example, SLU conducts research in the area, and in Denmark a large collaborative project is underway with the goal of developing an additive that can halve the methane emissions from dairy cows’ feed digestion.
