Outdoor production of slaughter pigs requires an optimized management to mitigate N pollution

Summary

In Danish outdoor pig production the sows are usually kept on grassland, while their progeny are transferred at weaning to indoor housing with access to an outdoor concrete pen.
It may seem paradoxical that a large part of meat consumed from outdoor systems comes from pigs that during the majority of their life have been prevented from natural behaviour such as rooting, digging and grazing. The explanation is the drawbacks of rearing growers outdoors including huge space demand, high work expenditure, high feed consumption and high environmental costs due to nutrient losses to aquifers and the atmosphere caused by high nutrient load and difficulty maintaining grass cover. However, it may be questioned if pigs reared indoors comply with consumers’ expectation for animal welfare in outdoor pig production systems. Therefore, systems need to be developed for growing pigs on grassland.