Sunday, 1 May 2016

The Beef Carbon Project - still plenty of room for improvement.

The Carbon Project is a massive undertaking by McDonald's to reduce the carbon footprint of their beef supplies in the UK and Ireland. It caught my attention because it was a finalist in this year's BBC Future Food Awards. They have reduced the carbon emissions from beef production by an average of 23% across 130 participating farms over 6 years. That is not enough to make me eat beef with abandon but it is certainly worth having. However what struck me in the report was that the worst farms generated 3-4 times more emissions than the best farms. This suggests there is a great deal more room for improvement.

Greenhouse gas emissions from rearer-finisher farms

This chart shows minimum, maximum and average greenhouse gas emissions from rearer-finisher farms. They breed their own cattle and raise them all the way to slaughter. Dairy beef farms have slightly lower carbon emissions because they raise cows that are not wanted from the dairy industry. The emissions from raising the mother count towards dairy products rather than beef. 

The method used to calculate emissions is approved by the Carbon Trust.

The bulk (78%) of the greenhouse gas emissions from the beef farms were to do with ruminant digestion, manure and fertilisers. Cattle and sheep generate methane from their guts, because of the way they digest grass and this is a very powerful greenhouse gas. There is also some methane produced from manure. Hence keeping the cattle healthy is an important part of reducing carbon emissions. Healthy cattle grow more quickly and convert feed to meat more efficiently producing less digestive gases. This also reduces costs.

Grass management is also very important. Using homegrown forage rather than bought in feed is an effective strategy for reducing emissions. (Soy based feed is particularly high in carbon emissions because it is a driver for global deforestation.) To get the most from grass the ideal is to use a paddock grazing system, where the cattle are shifted from one paddock to another in rotation. Grass grows slowly when it is very short, because there isn't enough green leaf area, and if it gets too long then it starts to die off so it is most productive when it is a medium length. The ideal is to let the cattle in when the grass is 10-15cm long and allow them to graze it down to about half that before moving on to another paddock [3]. Another useful strategy is to mix clover with the grass to reduce the need for artificial fertiliser.

The farmers grow other kinds of forage too such as maize and oats. One of them even used an alkali treatment on the cereals to make them easier to digest. This process was invented in Mexico and Guatemala around 1500 BC for treating maize, to make hominy. It helps to release important nutrients - without it people who eat mainly maize suffer from pellagra caused  by lack of vitamin B3 (niacin).

The figures for carbon emissions in the report are per kg live weight. Since we do not eat the entire carcass, the carbon emissions per kg beef are a bit higher. The overall average was 13.8 kg CO2e/kg l.w. so about 22 kg CO2e/kg meat. From my January post ('Are healthy diets bad for the environment') this is 25% better than the global average. Considered in terms of emissions per gram protein, the average was 85 gCO2e/g but the best was only about 37 gCO2e/g, not that much worse than (average) chicken (22) or lentils (21). Now if only we knew which farms were the best, we would know where to buy our meat. In the meantime I will continue to eat red meat only occasionally.

[1] BBC Future Food Awards (BBC) April 2016
[2] McDonald's Beef Carbon Report (McDonald's) Jan 2016
[3] Planning grazing strategies for better returns (Agriculture and Horticulture Development Board)

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