South West

Selecting for carbon footprint in UK dairy production


The use of selective breeding to improve the productivity of livestock systems has been carried out for centuries as a cost-effective approach to bring about change. In dairy cows, the focus has largely been on milk production traits (e.g. milk volume, milk fat and protein yield), until it became apparent that selecting animals solely on production traits impacts on animal fitness (e.g. health, fertility and lifespan). Therefore, selecting breeding animals on a range of production and fitness traits is now commonly done to enhance productivity and economic performance. Optimal health, fertility and survival are also important to minimising the carbon footprint of milk production. There are 1.8million dairy cows in the UK and milk production is worth almost £5billion to the UK economy.

The CarbonCow Index

Selecting animals based on their economic performance still favours the more valuable milk production traits. An alternative is a CarbonCow index which puts more emphasis on fertility and less on milk protein yield compared to other traits and indices available. The carbon values (kg CO2-eq./cow/lactation) derived could also be used to claim carbon credits. The carbon index is being trialled at Hartpury University and College dairy farm using genetic data (PTA = predicted transmitting ability for trait) and carbon weightings for important traits to identify breeding cows and bulls with a reduced carbon footprint as:

CarbonCow index (kg CO2-eq. per cow) = 0.12 × milk volume PTA + 5.55 × milk fat yield PTA + 1.04 × milk protein yield PTA + 0.84 × SCC PTA − 16.83 × calving interval PTA − 3.65 × lifespan PTA

Genetic selection is a cost-effective way to mitigate carbon emissions as the effects are permanent and cumulative with time and genetic selection information on a range of production, health and fertility traits for individual animals is widely available to farmers.

Key successes

The developed carbon index allows farms to identify animals with a lower carbon footprint and at the same time be more targeted with genetic selection of animals. The index values allow carbon credits as an incentive to the permanent changes being made at the farm level. This approach should support farms to quantify and mitigate emissions.

Selecting animals on their carbon footprint is now possible and timely. Doing so should help farmers identify low carbon footprint animals and reduce their emissions long-term. This novel approach supports the mitigation of emissions and carbon credit schemes for farms.

Key challenges

Historically the focus of genetic selection in livestock systems has been on increasing productivity and profitability. Targets for reducing carbon emissions, and improving animal health and welfare, has resulted in a growing demand for solutions to help farmers achieve future targets. Genetic selection is a cost-effective mitigation strategy as the effects are permanent and cumulative with time and breeding indices are commonly used. A breeding index with carbon weightings to derive individual animal carbon index values based on the carbon footprint of milk production was developed and trialled using Hartpury University and College dairy herd to explore the adoption of this approach. Selecting animals on carbon values puts more emphasis on fertility performance and less on milk protein yield, compared to selection economic values across a range of animal traits.     

Professor Matt Bell at Hartpury University says:

"Tools to monitor and mitigate carbon emissions are needed by farmers and the dairy industry. The CarbonCow index will allow farmers to be more targeted in breeding lower emission animals and potentially claim credits for reducing their emissions. The effects are permanent and cumulative with time and can be applied to all cattle populations."

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