Effect of Increased Somatic Cell Count and Replacement Rate on Greenhouse Gas Emissions in Norwegian Dairy Herds

Ṣeyda Özkan, Helge Bonesmo, Olav Østerås, Odd Magne Harstad


Dairy sector contributes around 4% of global greenhouse gas (GHG) emissions, of which 2/3 and 1/3 are attributed to milk and meat production, respectively. The main GHGs released from dairy farms are methane, nitrous oxide and carbon dioxide. The increased trend in emissions has stimulated research evaluating alternative mitigation options. Much of the work to date has focused on animal breeding, dietary factors and rumen manipulation. There have been little studies assessing the impact of secondary factors such as animal health on emissions at farm level. Production losses associated with udder health are significant. Somatic cell count (SCC) is an indicator on udder health. In Norway, around 45, 60 and 70% of cows in a dairy herd at first, second and third lactation are expected to have SCC of 50,000 cells/ml and above. Another indirect factor is replacement rate. Increasing the replacement rate due to health disorders, infertility and reduced milk yield is likely to increase the total farm emissions if the milking heifer replacements are kept in the herd.In this study, the impact of elevated SCC (200,000 cells/ml and above) and replacement rate on farm GHG emissions was evaluated. HolosNor, a farm scale model adapting IPCC methodology was used to estimate net farm GHG emissions. Preliminary results indicate an increasing trend in emissions (per kg milk and meat) as the SCC increases. Results suggest that animal health should be considered as an indirect mitigation strategy; however, further studies are required to enable comparisons of different farming systems.

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Agrawal, R. C. & Heady E. O., 1974. Operations research methods for agricultural decisions. The Iowa State University Press, Ames

Alford, A. R. et al., 2006. Jointly achieving profitabilty and environmental outcomes: Methane abatement from genetic improvement in the australian beef industry. Australian Agricultural and Resource Economics Society. Sydney.

Bartlett, P. C. et al., 1990. Milk production and somatic cell count in michigan dairy herds. Journal of Dairy Science, 73, pp.2794–2800.

Bell, M. J. et al., 2010. Effect of breeding for milk yield, diet and management on enteric methane emissions from dairy cows. Animal Production Science, 50, pp.817–826.

Bonesmo, H. et al., 2013. Greenhouse gas emission intensities of grass silage based dairy and beef production: A systems analysis of norwegian farms. Livestock Science, 152, pp.239–252.

Brink, C. et al., 2001. Ammonia abatement and its impact on emissions of nitrous oxide and methane—part 2: Application for europe. Atmospheric Environment, 35, pp.6313–6325.

Clark, H. et al., 2010. Mitigating methane in a systems context, Caxton Press.

Czerkawski, J. W. et al., 1966. The metabolism of oleic, linoleic and linolenic acids by sheep with reference to their effects on methane production. British Journal of Nutrition, 20, pp.349–362.

Eckard, R. J. 2010. RE: Greenhouse gas emissions from agriculture– reduction options.

Erisman, J. W. et al., 2010. Nitrogen and biofuels; an overview of the current state of knowledge. Nutrient Cycling in Agroecosystems, 86, pp.211–223.

FAO 2010. Greenhouse gas emissions from the dairy sector. A life cycle assessment. Rome, Italy: Food and Agriculture organization of the united nations (FAO), Animal production and health division.

Forster, P. et al., 2007. Changes in atmospheric constituents and in radiative forcing. In: Climate change 2007: The physical science basis. Contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. In: Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor and H. L. Miller (ed.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Harmon, R. 1994. Physiology of mastitis and factors affecting somatic cell counts. Journal of Dairy Science, 77, pp.2103–2112.

Hopkins, A. et al., 2009. A scientific review of the impact of uk ruminant livestock on GHG emissions. CRPR Research Report-Centre for Rural Policy Research, University of Exeter.

Hortet, P. et al., 1999. Reduction in milk yield associated with somatic cell counts up to 600 000 cells/ml in french holstein cows without clinical mastitis. Livestock Production Science, 61, pp.33–42.

Little, S. 2008. Holos, a tool to estimate and reduce greenhouse gases from farms: Methodology & algorithms for version 1.1. X, Agriculture and Agri-Food Canada.

Mcallister, T. A. et al., 2008. Redirecting rumen fermentation to reduce methanogenesis. Australian Journal of Experimental Agriculture, 48, pp.7–13.

Seegers, H. et al., 1998. Effects of parity, stage of lactation and culling reason on the commercial carcass weight of french holstein cows. Livestock Production Science, 56, pp.79–88.

Smith, P. et al., 2007. Climate change 2007: Mitigation: Contribution of working group iii to the fourth assessment report of the intergovernmental panel on climate change.

Stott, A. W. et al., 2010. Reducing greenhouse gas emissions through better animal health. Rural policy centre, policy briefing. RPC PB 2010/01.

Svendsen, M. et al., 2006. Somatic cell count as an indicator of sub-clinical mastitis. Genetic parameters and correlations with clinical mastitis. Interbull Bulletin, p.12.

Weiske, A. et al., 2006. Mitigation of greenhouse gas emissions in european conventional and organic dairy farming. Agriculture, ecosystems & environment, 112, pp.221–232.

Williams, A. et al., 2013. The benefits of improving cattle health on environmental impacts and enhancing sustainability. Sustainable intensification: The pathway to low carbon farming. Edinburgh 25–27 september 2013.

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