Livestock industries, including pig production
, are currently under scrutiny as to their environmental impact.
This scrutiny is expected to intensify parallel to rising concerns about climate change and the potential contribution of livestock to global warming.
Although the contribution per unit of meat from pig production systems to environmental impact is relatively low, pork is, at least for the time being, the most widely produced and consumed type of meat worldwide.
As a result, it contributes significantly to various types of environmental impact.
In 2013, the total contribution of pig production to greenhouse gas (GHG) emissions was estimated to be 668 million tonnes of CO2-eq. Which represents 9% of the total GHG emissions produced by animal production.
In addition, pig production is considered to contribute greatly to the acidification and eutrophication of the environment due to nitrogen (N) and phosphorus (P) emissions resulting from the storage and use of slurry in crop fields.
In some European countries, concern about these emissions is as relevant to their environmental agenda as concern about GHG emissions,
since, for example, pig and poultry production are responsible for 83% of NH3 emissions into the atmosphere in the EU.
Traditionally, improvements in pig husbandry and management have been aimed at increasing the systems’ effectiveness, especially in regards to the efficient use of resources such as feed.
⇀ Genetic improvement
For example, genetic selection has aimed to:
Increase growth rate
Improve carcass features, such as improving lean performance
Improve the reproductive performance of sows
⇀ Feed and nutritional improvement
Improvements in the use of feed
have also contributed to this, for example by:
The use of exogenous enzymes and synthetic amino acids
Advances in feed manufacturing technology
Any improvement in resource use efficiency will also improve the environmental impact of these systems.
This is because feed associated activities, including slurry management, are responsible for most GHG emissions in pig and other livestock systems. In the case of pigs, it represents more than 70% of the impact of these production systems.
Emissions associated with feed production
are particularly high if the Agricultural Land Use Change (ALU
) is taken into account. Involving deforestation linked to soybean production
for example. Which was the main source of protein for feeding pigs until recently.
Enteric methane emissions in pig production are negligible, but methane and nitrous oxide emissions from slurry are more noticeable.
Given this association between food-related activities and the environmental impact of pig production systems, it is not surprising that the production phase which con
tributes the most to the environmental impact is that of the fattening stage. Due to the fact that it is the phase where feed consumption is higher and feed utilization efficiency is lower.
Naturally, the opposite occurs in the transition phase
, especially in the case of early weaning piglets whose environmental impact is minimal
Taking all of the above into account, we have recently estimated the evolution of the environmental impact of pig production systems
in Great Britain over the last 20 years.
Given that almost 50% of sows in the UK are raised outdoors
, both conventional (intensive) systems and outdoor (extensive) production systems were considered.