What is the impact of mastitis on the carbon footprint of the dairy industry?

As I am writing this, world leaders are converging on Glasgow for COP26, with the primary goal to ‘Secure global net zero by mid-century and keep 1.5 degrees
within reach’, with the topic of one of the Presidency Programme events titled: Accelerating a just rural transition to sustainable agriculture (ukcop26.org). Interestingly, sustainable livestock production is not a key focus elsewhere in the agenda, one possible explanation being that global greenhouse gas (GHG) emissions from livestock & manure constitute a relatively small contribution to total global emissions (5.8% in 20161). Despite this, if we intend to achieve the ambitious targets being set at COP26, everyone needs to contribute to incremental decreases in emissions, including the dairy industry.

So how can we play our part in reducing emissions? The figure shows the different sources of emissions from a typical UK dairy farm, with the production of methane in the rumen from enteric fermentation being the largest contributor. Several important efforts are ongoing to directly mitigate enteric methane missions, however, even if methane production is halved or completely removed, this still leaves roughly 60 – 80% of dairy emissions unabated. To improve the overall emissions profile of a farm, it is not sufficient to only reduce methane production, improvements in efficiency must also be obtained. For every litre
of milk produced there is an overhead GHG cost, which can be increased or decreased through productive inefficiencies (for example diseases) or efficiencies (for example genetic improvements in production and fertility). This concept of efficiency is evidenced by modelling performed in the US dairy industry, demonstrating that improvements in performance between 2007-2017 reduced the GHG emissions per million metric ton of energy-corrected milk produced by 19%².

Zoetis is proud to be partnering with Kite Consulting and Livestock Sustainability Consultancy in the UK to better understand and quantify the impact that common
diseases have on dairy emissions and their associated economic costs, with the project aiming for completion in 2022. The diseases being modelled include mastitis, lameness, uterine disorders, and bovine respiratory disease, with fertility also being evaluated. Highlighting the importance of incremental improvements in animal health, David Levick, managing Partner at Kite Consulting, said that “the impact of a case of mastitis on the carbon footprint may seem small in the whole scheme of things, but we have a really tough challenge ahead of us to reduce dairy emissions by 30% by 2030. Every small contribution to this is going to help us achieve that goal. It is also in the farmers interest to do this too as the economic impact of a case of mastitis is very significant. In our work with farmers, processors, and retailers, we have found there is a strong relationship between cost of production and the carbon footprint. Lower disease incidence leads to lower
carbon, less waste and higher profitability. There is a logical linkage.” Dr. Jude Capper, founder of Livestock Sustainability Consultancy, emphasised the global relevance of the research, saying that “at the global level, we know that over 20% of animal protein is lost because of livestock disease, significantly increasing resource use and environmental impacts. Given the concerns around greenhouse gas emissions and climate change, we urgently need to know the relative impacts of livestock diseases on greenhouse gas emissions so that producers, processors and policy-makers can make evidence-based decisions about
livestock health.”

Returning to the topic of this article… what is the impact of mastitis specifically? While our project is modelling the impact of mastitis using data from the UK, there have already been studies published modelling the impact of clinical mastitis in the Netherlands3 and subclinical mastitis in Norway4. The Dutch research stimated that a case of clinical mastitis resulted in an additional 57.5kg CO₂ equivalents per ton of fat- and protein-corrected milk (FPCM) produced, a 6.2% increase. Using this information, it is possible to provide a crude estimate of the potential benefits of preventative animal health interventions in reducing farm emissions. Using existing literature and some back-of-the-envelope calculations, let’s look at a hypothetical example: What might be the potential annual GHG reductions if every dairy cow in Italy was administered with a teat sealant prior to calving?

• 1.643 million dairy cows in Italy 20185
• 7.51t FPCM per cow/year5
• 78238 cases of clinical mastitis prevented in 1 year if all Italian cows received teat sealant (number of cases needed to treat to prevent 1 case = 21)6
• 57.5kg extra CO₂eq. emitted per ton FPCM produced per case of clinical mastitis3
• 432kg extra CO₂eq. emitted per case on average (7.51t FPCM/cow x 57.5kg CO₂eq/t FPMC/case)
• This equates to a potential reduction of up to 33,837,696kg CO₂ eq. emissions, which is the same as 7359 passenger vehicles driven for one year, or 85 million miles of driving7

Although this is only a simple example it serves to demonstrate the potential significance of preventative animal health interventions. The good news is that usually interventions which have a positive impact on efficiency also have a positive return on investment, meaning that as we as an industry strive to improve environmental sustainability, we don’t have to sacrifice economic sustainability.

Text and picture: Andy Hancock

References:

1. https://ourworldindata.org/emissions-by-sector
2. Capper, Judith L., and Roger A. Cady. “The effects of improved performance in the US dairy cattle industry on environmental
   impacts between 2007 and 2017.” Journal of animal science 98.1 (2020): skz291.
3. Mostert, P. F., et al. “Estimating the impact of clinical mastitis in dairy cows on greenhouse gas emissions using a dynamic
   stochastic simulation model: a case study.” animal 13.12 (2019): 2913-2921.
4. Gülzari, Şeyda Özkan, Bouda Vosough Ahmadi, and Alistair W. Stott. “Impact of subclinical mastitis on greenhouse gas
   emissions intensity and profitability of dairy cows in Norway.” Preventive veterinary medicine 150 (2018): 19-29.
5. https://www.clal.it/en/?section=quadro_italia
6. Rabiee, A. R., and I. J. Lean. “The effect of internal teat sealant products (Teatseal and Orbeseal) on intramammary
   infection, clinical mastitis, and somatic cell counts in lactating dairy cows: A meta-analysis.” Journal of Dairy Science 96.11
   (2013): 6915-6931.
7. https://www.epa.gov/energy/greenhouse-gas-equivalencies-calculator