Discipline: carbon footprint; Keywords: climate change, rumen fermentation, manure, beef cattle, dairy cattle, smallstock, pigs, poultry, game.
Methane emissions are of interest because of the concern that the climate change that is beginning to affect the globe is largely the result of increased greenhouse gasses (GHG) entering the atmosphere and troposphere. The increase is thought to be the result of increased industrialization, deforestation, increased populations, energy from non-renewable resources, and also more livestock numbers to feed humans. Governments worldwide have committed themselves to limit GHG emissions, also South Africa, by reducing output by 20-30% by 2030. That also applies to livestock agriculture, even though livestock contributes less than 10% of total emissions.
To do that countries in the first instance need reliable figures of the current status, in order to understand where they should go. The dilemma in South Africa is that the official figures for livestock methane emissions are inaccurate and this situation had to be rectified. A Research Project was consequently registered at RMRD SA, but although the Red Meat Industry took the initiative, other livestock industries including the Dairy Industry also contributed to the budget. The methane emissions from enteric and manure emissions have now been calculated by UP PhD student Linde Du Toit which will be included in his thesis. Some of these figures have also been included in a study with the title: “The Status, Socio-economic and Environmental Impact, and Challenges of Livestock Agriculture in South Africa”, by H.H. Meissner, M.M. Scholtz and H.C. Schönfeldt, available at www.RMRDSA.co.za. A summary of enteric plus manure methane emissions is shown in the table below. The figures include estimations of both commercial and emerging/communal sectors.
LIVESTOCK SPECIES METHANE EMISSIONS (Gg/year)
Beef cattle 648.4
Dairy cattle 140.5
Horses, donkeys and mules 6.52
Poultry (all species)* 0.03
Game (in private ownership) 129.3
*The figure of poultry is low because their digestive tract produces very little methane.
The contribution of dairy cattle to the total of all livestock species is about 11%. One can also express the methane emissions in relation to the contribution to food supply and revenue. Expressed in this way methane emissions are 50 g/kg milk produced and 14.5 kg per R1000 contribution to GDP which is the least methane of all species, even if fresh milk because of the high water content is converted to dry matter. This is because milk production is an efficient process and the cow herself produces the product whereas e.g. in meat production the progeny produces the product, while the mother is responsible for the most methane emissions. Compared to developed world figures the South African figures compare favourably, although life cycle analyses still need to be done. Preliminary figures are 1.3 – 1.5 kg CO2 equivalent/kg milk in comparison to 0.84 – 1.4 kg CO2 equivalent/kg milk in the major dairy producing countries.