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Is methane really the problem? (Feb 23)

The drive to reduce dairy emissions is essential for the future of the industry – and the planet. But should methane really be producers’ focus, particularly when businesses are facing more immediate on-going pressures?


Methane is undeniably a component of dairy emissions, but its headline billing in much of the debate on the subject is questionable. Current thinking from RABDF and AHDB Dairy is that dairying is responsible for around 2% of total UK emissions, with enteric methane accounting for just under half of this, so that’s less than 1% of UK total emissions. You can’t see it, you can’t smell it, and you certainly can’t measure it practically on farm, yet methane is at the epicentre of current debate to reduce dairy cow emissions.

Methane has been flagged up as a problem principally because it has 25 times the warming impact of carbon dioxide (CO2), which means that it is seen as a major contributor to global warming. While it is a more potent greenhouse gas (GHG) compared to CO2, it also has a comparatively short life in the atmosphere. CO2 remains in the atmosphere for around 1,000 years, but methane stays there for just 12. So should producers be focusing on a short-term problem, particularly as UK dairy units have already lowered their methane output in recent years, something conveniently ignored by some targeting the industry.

There are fewer dairy cows and heifer replacements in the UK now compared to just 20 years ago, so the industry is already producing less methane and reducing emissions. In 2000 there were 2.336 million dairy cows in the UK but by 2020 this had fallen to 1.856 million – a 20% reduction. Looking at the past decade in more detail, between 2010 and 2020 dairy numbers crept up by 1%. But the number of replacement heifers that were more than 25 months old fell by 38%, and there were 3% fewer replacements aged less than two years old.

Unrecognised progress

By reducing cattle numbers, dairy units are already producing less methane, helping to lower environmental levels. Yet this significant progress in reducing methane emissions has largely been unrecognised.

So how did methane even become such a hot topic? It didn’t start at farm level, but is being driven, in part, by campaign groups and NGOs opposed to dairying who have picked up on the emissions resulting from milk production, and have contributed to the conversation to make methane sound far worse than CO2.

Cow burps: focusing on methane deflects the debate away from wider issues

Methane generated by human activity is rarely, if ever, flagged up and the focus on dairy and livestock farming serves to deflect the debate away from the real issue of emissions from the wider population. As dairy producers have no representative organisation that speak on behalf of them all, the counter arguments are not made sufficiently robustly. And, currently, there are no signs of a will to address this messaging imbalance in the industry.

Several supply companies are now urging producers to use feed additives that they claim will impact rumen fermentation and reduce enteric methane production, but there are unanswered questions.

Methane production

Products developed specifically to reduce methane, including those based on seaweed extracts, essential oils and other chemicals, come with some impressive claims, typically talking of reductions in methane production of as much as 50%, although this is impossible to measure and validate on working farms.

To achieve this, these products need to be fed 365 days of the year to both milking and dry cows. The quantity needed per cow per day varies hugely, depending on the specific product. Some require just a few grammes per cow per day, such as essential oils. Others, based on seaweeds or nitrates need to be fed at a rate of between 1.5% and 2% of dry matter intake, so around 360g/day. Clearly there are some significant practical issues to be ironed-out when including the products in diets.

Most of the research has been in TMR-fed herds where it is more practical to feed the quantities required. But what happens in grazing systems with no buffer feeding? Or where cows are just fed dairy compounds to yield in the parlour? What are the practicalities of achieving the target daily intakes where concentrate intakes vary according to yield? Will cows on higher feed rates be over-supplied at increased cost? More research is required to answer these and other fundamental questions, but it does seem that these products may not be practical in all systems.

And they are not cheap, with estimates of between 15p and 30p per cow per day being quoted and for what financial return? Unless feeding methane reduction products is somehow monetised, producers will just see an increase in annual feed costs of between £50 and £100 per cow. And they will have little or no evidence to show if the product has been effective.

On most, if not all, dairy units, reducing methane production needs to be incorporated into a more holistic approach to cutting emissions. Many existing approaches have the potential to reduce emissions without incurring greater costs, allowing environmental and economic sustainability to increase in tandem. And these are usually measurable so producers can assess the results.

Cut emissions

Reducing replacement rate, lowering age at first calving, removing soya from diets, cutting silage waste, improving nitrogen-use efficiency, and increasing feed efficiency will all help to cut emissions and contribute, demonstrably, to the business’s bottom line. The same cannot be said for focusing on methane reduction alone.

When the time is right to consider a product to help reduce methane, it will be important to ensure there is sufficient robust, independent research and make sure to get a third-party opinion on this. Challenge whether the product is appropriate to your system and if there is research to demonstrate that it is. For example, if included in compounds, what is the impact on performance and cost of feeding variable amounts per milking? And ask the supplier how to verify the product is working and how to achieve a return on investment.

to reduce emissions, including methane, from dairying is important, but the industry must make sure it is allowed to focus on its own priorities. It’s questionable whether or not methane reduction is one of them.

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