Guest Columns

Dairy Research

Dairy’s key sustainability role

John Lucey

John Lucey, director of the Wisconsin Center for Dairy Research at the University of Wisconsin-Madison, contributes this column for Cheese Market News®.

The dairy industry is very focused on efforts to reduce its greenhouse gas (GHG) emissions and contribute positively to efforts around climate change and sustainability. Much of those environmental impacts are at the farm level due to factors like enteric fermentations (e.g., release of methane from the digestion of grass/feed by the rumen fermentation), release of GHGs from manure and use of water/land for feed production.

However, it’s important to put this in the context that dairy only makes up 2% to 3% of overall GHG emissions but is a key contributor to methane emissions.

Some of the U.S. public seem to think that increasing cow numbers have been a significant contributor to recent climate issues. However, cow numbers have dramatically decreased in the U.S. from around 25.6 million cows in 1944 to around 9.4 million today. Between 1944 to today, the average milk yield per cow has increased from around 4,500 pounds per year to over 24,000 pounds per year. This remarkable increase in the efficiency of milk production (due to advances in breeding, feeds, management, etc.) has allowed the U.S. dairy industry to produce more milk today from a little more than a third of the animals it needed around the time of the Second World War. Between 2007 and 2017, U.S. milk production increased by about 25%, but total GHG emissions hardly changed due to ongoing improvements in the efficiency of milk production.

Despite claims from some activists, recent studies have demonstrated that removing all farm animals from U.S. agriculture only reduced total GHG emissions by 2.6%, once you account for other types of food production that would be needed to supply all the required nutrients previously provided by dairy. This would be a huge disruption for very little environmental gain.

Let’s discuss methane in a little more detail. Methane, the primary gas released by the cows, is a short-lived GHG with an atmospheric life cycle of about 10 to 12 years. Atmospheric methane is constantly being broken down into CO2 that is then captured by plants as part of the photosynthesis process; these plants are eaten by cows who then release methane, starting this cycle over again. Methane is a potent GHG, which explains the focus in reducing its emissions. It should be noted that the CO2 from fossil fuels has an atmospheric life cycle of around 1,000 years, so what we have released up to now will continue to warm the planet for nearly a millennia. California recently announced that it was well on its way to achieving its target of reducing dairy methane emissions to 40% below 2013 levels by the year 2030. Their efforts are focusing on reducing cow numbers, improved manure management, use of digesters to capture and utilize methane, and enteric methane reduction strategies. Ongoing research efforts are exploring breeding cows that produce less methane and new feed additives that have the potential to significantly reduce enteric methane.

If the number of cows in the U.S. was static for the last 20 years (actually, it has been declining), then there was no additional global warming due to methane emissions from cows. This is because methane is part of a carbon cycle and atmospheric methane is constantly being broken down as new methane is emitted; there was an initial warming impact from methane emissions when the number of ruminant animals increased in a region. Before dairy cows arrived in the U.S., it has been estimated that there were over 60 million bison and countless other ruminant animals like elk and deer. So, it is unclear to me if there has been a major change in enteric methane emissions from ruminant animals since the Europeans arrived in the U.S. — probably it has increased due to the higher production efficiency of cows and beef animals. Looking at this another way, reducing methane emissions is of interest as a short-term approach to try to slow down (maybe even have a cooling impact on) the planetary warming that is primarily caused by the utilization of fossil fuels (releasing CO2).

We could also consider what is the lowest level of GHG emissions that are required to produce a set amount/volume of milk. Then we can work to steadily reduce the level of GHG emissions involved in producing that volume of milk. I believe the dairy industry has a critical role in providing consumers with essential nutrients, but can we at the same time balance this critical function with our climate impact and improve our GHG emitting efficiency? A published analysis showed that the carbon footprint per billion kilograms of milk produced in 2007 was only 37% of an equivalent milk production in 1944. Improving production efficiency is therefore the key to mitigating environmental impacts. A big challenge is that in developing countries, the milk production per cow is significantly lower, thus the efficiency of GHG emissions per cow is much poorer. Working with developing countries to adopt modern milk production and breeding strategies would allow them to significantly reduce their cow numbers (while still providing enough milk to feed their populations), and this would ultimately reduce the global GHG emissions from the dairy sector.

There are also emerging ingredients or feed additives that could help significantly reduce methane emissions per cow (e.g., there are reports from some of a more than 80% reduction in methane production). These feed supplements affect rumen bacteria, specifically certain bacteria that produce methane, and feeding these compounds to cows results in less methane. A lot of countries are looking at this as an option; however, there is still work that needs to be done in this area. In the European Union, the feed additive 3-NOP (3-nitrooxypropanol) was recently deemed safe by regulators and claims reductions of 20% to 35% in methane emissions in cows. Other countries have also approved the use of 3-NOP including Brazil and Australia, but the FDA approval process is very slow in the U.S. Another type of feed additive is derived from seaweed with the active compound being bromoform; ongoing research is evaluating its efficacy and safety. California recently approved one seaweed product as a feed additive, but none have yet been approved nationally by the FDA. The Center for Dairy Research (CDR) will be collaborating with the U.S. Dairy Forage Research Center on a project evaluating one of these seaweed additives on milk quality.

At the farm level, improved manure management practices are being explored including liquid/solid separation systems and the installation of digesters. The natural gas produced by these digesters can be captured or used to run a generator that can produce electricity for use on the farm or put back into the grid. Some bottlenecks include permitting and rezoning, and along with other farm-based renewables, there is a need for a competitive rate for any electricity produced on-farm to incentivize these investments. There is also significant research on strategies related to regenerative agriculture, which essentially is trying to help keep more carbon in the soil (which is a significant sink or trap for carbon).

The complicated question is how do we make these strategies cost-effective and worth the investment from our farmers? At dairy processing plants we can also play our part in the circular bioeconomy by better utilization of low-value byproducts like whey permeate and converting them into green chemicals like bioplastics, organic acids and bioalcohols. The CDR is also supporting efforts in that area. Currently almost all chemicals are derived from fossil fuels, and they are not renewable sources. The dairy industry is making a significant effort to address current climate challenges. There are a lot of opportunities if we can figure out the best approaches, which will take significant research and various stakeholder collaborations.


The views expressed by CMN’s guest columnists are their own opinions and do not necessarily reflect those of Cheese Market News®.

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