RECENT ESTIMATES OF GREENHOUSE GAS EMISSIONS (GHG) OF DAIRY CATTLE

Cattle in South Africa produced a total of 35.37 million tonnes (Mt) of carbon dioxide equivalent (CO2 e) emissions in 2019, inclusive of emissions from pasture, range and paddock. Methane (CH4) from enteric fermentation accounted for 64.5% of the total emissions followed by emissions from pasture, range and paddock (27.7%). Manure management contributed 4.34% of N2O (nitrous oxide) to the total emissions while this source also produced 3.45% of CH4 emissions. Commercial beef was responsible for 50.2% of the total emissions, followed by subsistence beef (36.7%), commercial dairy (10.5%) and feedlot cattle (2.52%). For commercial dairy cattle the numbers in Mt CO2 e are respectively: cows – pasture 0.55, mixed 0.94, TMR 1.02; heifers 0.61; calves 0.55; young bulls 0.04; mature bulls 0 02; total 3.73 Mt CO2 e per year (2019). According to Lacto Data Volume 23 (1) of May 2020, the unprocessed milk purchase in 2019 was 3.433 Mt, which implies that the GHG emissions per litre milk were 1.09 kg CO2 e in the commercial dairy sector. Meissner et al (2013) estimated the GHG emissions as 1.3 – 1.5 CO2 e/ℓ milk, Reinecke & Casey (2017) 1.36 kg CO2 e/kg FPCM and Galloway et al (2018) 1.39 kg CO2 e/kg ECM on pasture-based systems. The number will be about 10% higher if milk output is fat and protein or energy corrected, although it may also be influenced by slightly different emissions factors used by the various authors. Thus, the 2019 number may increase to about 1.2 kg CO2 e/kg ECM or FPCM. This suggests an improvement and also a favourable comparison to major milk producing countries.

Reference:

 M. I. Tongwane & M. E. Moeletsi, 2021. Provincial cattle carbon emissions from enteric fermentation and manure management in South Africa. Environmental Research 195 (2021) 110833