Dairy Vets and Cows in New Zealand milking parlour

Agriculture remains a cornerstone of the New Zealand economy and ruminant based agriculture, particularly dairy, makes up the largest single component. As a direct result of this, methane emissions from ruminants contribute around one third of the country’s total greenhouse gas emissions. Reducing these emissions is critical to New Zealand meeting its international targets but doing so comes with a considerable risk of damaging the economy.

There has been considerable discussion over the last two years about this conundrum. The recent announcement by the New Zealand government that, from 2025, it will tax methane emissions from farms has attracted considerable attention.1 It has been reported that New Zealand is the first country to do this. Previously farming had been exempted from emissions trading. The new scheme, which still has many details to be filled in, will allow farmers to offset emissions via tree planting and will incentivise the use of technology to reduce methane outputs.2  There are no plans at this time to include carbon sequestered into soil on farms in this scheme, because the scientific picture remains unclear.

While agriculture bears the brunt of the problem in New Zealand, it must be remembered that internationally there are many other important sources of methane including transportation, increased usage of natural gas and emissions from rubbish dumps. Nearly 40% of all methane originates from the natural decomposition of plant material in wetlands and the recent spike in atmospheric methane has been blamed mainly on fracking activity.3 A more accurate assessment of methane’s influence on global warming can be gained by applying  the GWP* metric. This  suggests that over time, methane is less impactful than the GWP100 metric implies but this is no "get out of jail card" ; methane originating from agriculture must be addressed but serious reduction of food production cannot be contemplated.

Is it possible to make significant reductions in methane and maintain a dairy industry? A recent report from Finland suggests that this is achievable. The authors’ report that over a sixty year period, methane emissions from the Finnish dairy herd reduced by 56%.  The main reasons for this were improvements in milk yield from fewer cows, which were functions of both better breeding and feeding.4

The same authors noted that methane intensity per litre of energy corrected milk is a function of the number of cows, milk yield, replacement rate and the diet composition. It is interesting to note that veterinarians can have direct influence on most of these, particularly on replacement rates, which will be impacted upon by improved fertility and better disease control.

At VetSalus we are committed to increasing the positive impact of the profession in these areas. Our forthcoming online course “A Veterinary Approach to Sustainable Food and Farming” aims to increase veterinary knowledge about sustainable farming and increasing engagement of the profession in this area.5 And as the Finnish work suggests, there are numerous opportunities to ensure that the valuable sources of protein and energy supplied by dairy can continue to be produced, while reducing their methane contributions.

No-one doubts that methane is a potent greenhouse gas and all incentives to reduce emissions are to be encouraged. The New Zealand initiative will certainly bring focus on the issue in that country but it is also to be hoped that the science of soil carbon sequestration will develop to paint a fuller picture of what is actually happening on New Zealand’s farms.

For more information on the course, which is due for worldwide release in July see www.vetsalus.com or email [email protected]