Comparative environmental assessment of three systems for organic pig production in Denmark

Summary

Organic pig production has emerged as an alternative to the intensive conventional pig production in Europe with the animals confined indoors and often an imbalance between livestock and land for feed production and manure utilisation. The organic systems aim at improving animal welfare by supporting the pig’s natural behaviour (Hermansen et al., 2003), and improving soil fertility by better linking crop and livestock production from an agro-ecological point of view.
The differences between organic and conventional pig production is more fundamental than for example differences between dairy production systems, which may be why the share of pig herds within the organic holdings is considerably lower than the percentage of pig herds in conventional agriculture in both the UK (ADAS, 2001), Germany (Willer, et al., 2002) and Denmark (Plant Directorate, 2004b). However, the recent development has seen a dramatic increase in demand for organic pig meat in Denmark, Germany and the UK and present production cannot meet demand. Besides regulation on use of feedstuffs, the organic pig production has a main challenge in the regulation for housing. The sows need access to grazing in the summer time, and growing pigs need as a minimum requirement access to an outdoor run. In addition, the area requirements for indoor housing are higher than for conventional production.
These requirements have a major impact on what systems to consider, both from economical and agro-ecological points of view. And therefore, efforts to improve organic pig production should focus on the integration of livestock production and land use, but considering environmental impacts on local and global scales.
The most commonly used system in Denmark is to combine an outdoor sow production all year round with rearing growing pigs in barns with an outdoor run (Hermansen & Jakobsen, 2004). The type of stable most commonly used by full time producers in Denmark is a system with deep litter in the entire indoor area or deep litter/straw bed in half the area while the outdoor area consists of a concrete area. The use of a concrete covered area, from which the manure can be collected, is a way to comply with the environmental regulations stating that the outdoor run should be constructed in a way that prevents leaching.
Research shows that very good production results can be obtained in such systems in terms of litter size, daily gain, feed consumption and health (Hermansen et al., 2003). However, two possible drawbacks exist. First, the space requirement per growing pig in housing facilities is considerable and, thus, capital demanding. For fattening pigs of 85-100 kg live weight, the indoor space required is equivalent to 1.3 m2/pig (of which at least 0.65 m2 must consists of a solid floor) and 1.0 m2 outdoors run (Council Regulation, 1999). In addition, each lying zone, i.e. straw bedding area, must be able to accommodate all pigs at a time. This put a heavy burden on costs of buildings (money and resource use) and at the same time it can be questioned if such rearing systems comply with the consumer expectations. Second, the outdoor sow production has been connected with high environmental burden in the form of N losses (Larsen et al., 2000; Eriksen et al., 2002).
This made us to consider two alternatives to the organic pic system most often used presently. A system where all pigs were reared outdoors on grassland (and saving buildings) and a system where sows and growing pigs were kept in a tent system placed upon a deep litter area in order to reduce risk for N leaching. Both have been used under commercial conditions. In order to assess the possible trade-offs between environmental impacts on the one hand and the assumed advantages of these alternative systems (animal welfare, low investment) on the other hand an Environmental Impact Assessment was needed. Environmental assessment of livestock farming systems can be done on an area basis (e.g. nutrient losses per ha) or on a product basis (e.g. Green House Gas emission per kg meat or milk; Haas et al., 2001; van der Werf & Petit, 2002; De Boer, 2003; Halberg et al., 2005). The area based assessment is relevant for locally important emissions such as nitrate leaching but a product based assessment is more relevant for emissions, which have a less localised impact (acidification) or even a global character (Green House Gasses). Moreover, since the organic production is often considered a more sustainable alternative to conventional intensive pig production, from a consumer point of view it might be interesting to compare the eutrophication per kg meat produced from different organic and compared to conventional systems.
The objective of this paper is to compare the environmental impact and green house gas emission of organic pig production systems with different levels of integration of livestock and land use.