Minskad klimatpåverkan med vallfoder till gris: beräkning av klimatavtrycket ur ett livscykelperspektiv

The purpose of this study was to estimate the climate effect from a life cycle perspective of introducing grass-clover biomass as an ingredient in diets to pigs in conventional Swedish pig production. The results show that the climate footprint of one kg of conventional pork can be reduced by around 13 percent by replacing parts of the pigs' traditional feed with grass-clover biomass. The reduction in emissions is due to i) lower nitrogen application to grass-clover ley compared to grains and thus lower nitrous oxide emissions and lower emissions from mineral fertilizer production, ii) reduced diesel use, iii) higher yield for grass-clover ley compared to other fodder, and iv) precursor crop effects from the cultivation of grass-clover ley. If the expected sequestration of carbon in soil from the introduction of ley in a cereal-dominated crop rotation is included, emissions are reduced by an additional 18 percent. However, the estimate soil carbon sequestration is uncertain and the process is reversible, why this reduction potential must be considered with some caution. There are several additional benefits of introducing grass-clover biomass into pig production including improved pig welfare, increased soil fertility, increased diversity of crops grown on farmland which can benefit biodiversity and reduced use of inputs. To grow ley and use it as a feed ingredient in diets to pigs, a different type of machinery and feeding equipment is needed than what is traditionally used in pig production. However, it should be possible to put in place such technology quickly as such systems are already used in milk and beef production. Advisors in pig production also need information and knowledge about which ley crops are suitable for pigs and how technical solutions for harvesting, storing and handling ley at farm level should take place. Much of that knowledge can be obtained from milk and beef producers.