With a growing focus on practical ways to reduce greenhouse gas emissions, methane suppressing feed products (MSFPs) are gaining attention within dairy systems. One option is calcium ammonium nitrate (CAN), also referred to as nitrate. CAN is a dietary source of non-protein nitrogen and calcium, which has shown potential to reduce enteric methane emissions when incorporated into cattle rations.
Nitrate works by acting as an alternative hydrogen sink in the rumen. Instead of hydrogen combining with carbon dioxide to form methane, it is redirected to reduce nitrate into ammonia. This shift in rumen fermentation can result in lower methane production. It is possible to incorporate CAN into rations in several ways, including within concentrates or by mixing with carriers such as molasses.
A key consideration when feeding CAN is the need for a gradual introduction. Sudden inclusion can increase the risk of nitrate toxicity, so careful management and monitoring are essential, particularly in extensive grazing herds, where nitrate accumulation in forages may occur. Balancing the ration for rumen degradable protein (RDP) is also important to ensure efficient use of ammonia in the rumen and to minimise nitrogen losses through urinary excretion.
What does the evidence say?
Research indicates that nitrate supplementation can deliver methane reductions in the region of 15–20% under certain conditions. Most studies show little effect on daily milk yield or milk fat content but there is often a small decrease in milk protein content and a reduction in feed intake of around 1kg dry matter (DM) a day. In many studies, this decrease is paired with small improvements in feed efficiency, suggesting that CAN could improve nutrient use in cattle.
As with any ration change, outcomes depend heavily on the wider feeding strategy, ration balance and overall herd management. The level of inclusion and how nitrate is introduced are particularly important factors influencing both emissions and performance responses. If feed grade urea is currently being fed as a source of non-protein nitrogen, then replacing urea gradually with CAN is straightforward.
How does this fit on farm?
For farms involved in the UK Dairy Carbon Network (UK-DCN), the use of CAN will depend on individual system requirements, feeding approaches and business priorities. There is no one-size-fits-all solution, and decisions should be based on robust evidence and practical feasibility.
Farm Liaison Officers and technical teams within the UK-DCN are working with participating farms to explore these options, helping to interpret the latest research and assess how different strategies could perform under real farm conditions.
CAN represents one potential tool within a broader approach to reducing emissions. While results can vary, it offers a practical, nutrition-based option that can be implemented within existing systems, contributing to improved efficiency and a lower environmental footprint when carefully managed.
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