Diversification is regularly promoted as a way to improve the sustainability of agricultural systems. Pigs’ omnivorous qualities give them a special place in diversified farming systems. The INRAE experimental farm in Mirecourt has been converted to organic farming for 15 years. Since 2016, animal production (dairy cattle and suckler sheep in strict herbivory, fattening pigs) and plant production (cereals, grain legumes, oilseeds, fresh vegetables) have been diversified. This diversification makes it possible to explore pig-rearing systems that use only farm products that cannot be used for human consumption (from sorting cereals, vegetables, non-marketable milk). For 3 years, a herd of about 30 fattening pigs is reared each year in the open air under rotational grazing arrangements on alfalfa paddocks. Rations are determined according to the resources available in the diversified system without seeking to maximize animal growth. We observe average growth of 420 g live weight/d (± 82 g/d) and lean meat rates of 66.4% (± 2.7%), for an average carcass weight of 94 kg (± 13 kg). However, these results conceal significant heterogeneities in growth but also over the fattening period (228 d ± 74 d). Deriving value from animals through a short supply chain (traditional butchery) makes it possible to use certain mechanisms that cannot be transposed into systems managed in batches, while providing added value to remunerate the work (34.5 €/hour). Voluntarily constrained, this pig-rearing system is part of a system that is driven by a rationale of strong autonomy and economies of scale and that develops crop-livestock interactions, which makes it difficult to compare to specialized systems.