Reducing the carbon footprint of dairy cows
One environmental issue on the horizon is climate change and how dairy farms can reduce their carbon footprint.
Brian Finch, an agri-environment advisor with the College of Agriculture Food and Rural Enterprise (CAFRE) said: “With more environmental pressures on farmers and direct support likely to change in the future, it will more important than ever that farm businesses aim to be sustainable both economically and environmentally.”
Robert Bryson from Loughbrickland is a member of one of CAFRE’s dairy business development groups and has carried out a carbon footprint for the dairy enterprise in 2018 as part of the Dairy-4-Future project.
The farm consists of 210 Holsteins Friesian cows with an annual milk yield of 9,600L from 2.5t of concentrate per cow.
Brian said: ”Robert’s dairy enterprise carbon footprint was calculated at 0.99kg of CO2 equivalent per kg milk corrected to 4% fat and 3.5% protein.
”This is well below the Department of Agriculture, Environment and Rural Affairs (DAERA) farm business survey average of 1.24kg of CO2 equivalent per kg milk.”
“Methane is the biggest green house gas (GHG) and is responsible for about 50% of emissions, so milking top performing healthy cows for as long as possible will help lower the footprint,” Brian said. Robert has a replacement rate of 22% and calving interval of 385 days.
Robert aims to breed cows that will last at least four lactations. The average lifetime performance per cow is currently 40,000L compared to the Northern Ireland (NI) average of 23,000L.
”Nitrous oxide is next biggest GHG on a dairy farm, with the main source from spreading slurry and fertiliser, accounting for about 30% of emissions on NI dairy farms,” Brian added.
”Nitrous oxide is about 300 times more potent than carbon dioxide. Robert has been using low emission slurry spreading [LESS] and spreads the majority of slurry from late February to May.”
Brian went on to say that ”concentrates contribute approximately 10% of GHG emissions from dairy farming. Robert targets his concentrate feeding by feeding to yield in the parlour only with silage easily fed ad-lib”.
”Robert’s feed rate is currently 0.26kg/L. He also aims to maximise his milk from forage (MFF) which stands at 3,900L per cow, which is above the benchmark average of 1,960L.
Robert aims to have all cows out by end of February for 2-3 hours grazing and out full-time by end of March. Silage quality is paramount.
”The remainder of the emissions in the form of carbon dioxide, are from electric and fuel use. About half the energy costs for dairy farmers are associated with milk cooling and heating water for cleaning and operating vacuum pumps.
”Electric use can be reduced by using a heat exchanger to recover the heat released from milk cooling. Using solar PV panels to heat the water could also be considered and using LED lighting which Robert has already installed.”
Brian concludes that “in Northern Ireland there is a wide range of production systems, from total confinement to spring calving grass based systems”.
”Studies have shown there is more emission intensity variability within a production system than between systems, perhaps as much as 30%. Maximising efficiency within a system is more important than the type of system used”.