The carbon footprint of British pig farming has reduced by almost 40% over the last 20 years – making pork a much more environmentally friendly meat for consumers, suggests a study.
The independent research is based on conclusions from historic data on livestock systems across England, Scotland and Wales. Because data on agricultural inputs was sparse, a new methodology was developed to retrospectively estimate their contribution.
The study was led by the Institute for Global Food Security (IGFS) at Queen’s University Belfast, Northern Ireland. Agricultural systems have come under pressure to reduce their carbon footprint and the UK government has set a target of carbon neutral farming by 2050.
Research leader Ilias Kyriazakis said: “The reason this research is so significant is that it shows an area of livestock farming where carbon footprint has been reducing over the past 20 years, almost under the radar.
“We hear a lot these days about the need for farmers to reduce their carbon outputs for the sake of the environment, especially as it applies to beef and dairy cattle farming. There is much more attention focused on ruminant food systems as they produce higher greenhouse gas emissions.”
Calculating the carbon footprint of a farming system is a complex metric. It involves a large number of indicators including what kind of fuel is used on the farm, how soil is cultivated, the style of land management and the types of animals and crops farmed.
Although the environmental impact contribution per unit of meat from pig systems is relatively low, pig meat is the meat type most produced and consumed globally. Scientists says it therefore contributes significantly to several forms of environmental impacts.
The study estimates that pig production systems contributed 668 million tonnes of carbon dioxide to greenhouse gas emissions in 2013 – roughly 10% of emissions produced by livestock systems overall.
In addition, pig production systems are considered to be major contributors to the acidification and eutrophication of the environment. This is due to emissions of nitrogen and phosphorous from manure storage and spreading.
The new study suggests an overall drop in the carbon footprint across the British pig sector. This amounts to a 37% reduction in emissions for indoor production systems and a 35.4% reduction for outdoor-bred pigs.
The role of animal feed was found to be central to the environmental impact of pig farms – accounting for between 75-80% of carbon footprint. Changes to feed ingredients, therefore, had the potential to significantly alter the carbon rating of pig farms and the industry as a whole.
More specifically, the increasing trend of replacing soya imported from South America with home-grown crops such as rapeseed and sunflower meal to feed pigs was found to have a significant mitigating effect on environmental outputs.
Advances in animal nutrition and feedstuff availability were also found to have had a beneficial effect, particularly the increased availability of synthetic amino acids and enzymes, the price of which decreased over the time period in question.
When added to domestic feedstuffs like rapeseed, these supplementary ingredients increased nutrient availability and improved feed balance, which was found to have reduced nutrient excretion in manure while boosting animal productivity by as much as 30%.
The study also found that such supplements in animal feed helped lower levels of phosphorous in run-off from pig manure by more than 20%, reducing the contribution of pig systems to freshwater pollution.