In organic farming systems forages play a fundamental role, either in crops rotation for soil fertility preservation, either in livestock feeding. In particular for ruminants, which diets forages must represents at least 60% of d.m., forage availability, quality and feeding techniques largely influence animals yield, as well as their health status and products quality. Botanical composition (leguminous, grass, weeds), use of fertilisers, stage of maturity and conservation techniques largely influence forage quality. Cattle, in particular dairy cows, diets should be supplied with mineral and vitamin supplements to get out of their forage inadequate or variable contents. Despite grazing is considered essential to livestock in organic farming, economical reasons as well as pedological and climatic characteristics of many Italian area will probably limits its possibility to become a major technique of forage utilisation but, where put into practice, to be efficient grazing management needs high professional skills. Harvesting and conservation have to be properly managed in order to obtain forages with high nutrients contents and to prevent fungal and microbial deterioration. Ensiling can help in avoiding some negative aspects of haymaking and limits to silage use in livestock feeding should be reconsidered. Knowledge in animal science has been largely improved during the past decades, but it mainly focused on intensive livestock breeding systems. Despite this, organic farming systems must not reject this patrimony but, on the contrary, they strongly need this knowledge to develop ecologically sustainable, economically feasible and socially acceptable production systems.