Feed production is an important contributor to the environmental impacts caused by livestock production. In Portugal, non-dairy cattle are commonly fed with a mixture of grazing and forages/concentrate feed. Sown biodiverse permanent pastures rich in legumes (SBP) were introduced to provide quality animal feed and offset concentrate consumption. SBP also sequester large amounts of carbon in soils. Here, we used a comparative life cycle assessment approach to test the substitution of concentrate through installation of high-yield SBP. Using field data for the Alentejo region in Portugal, we compare the global warming potential of a baseline scenario where cattle is fed in low-yield, semi-natural pastures supplemented with feeds that vary in the ratio of silage to concentrate, and a second scenario where the feed is substituted with high-yield SBP. Although SBP use more fertilizers and machinery, this replacement avoids the emission of about 3 t CO 2 eq/ha even after SBP stop sequestering carbon. Using crude fiber to establish the equivalence between scenarios leads to higher avoided impact, owing to the fact that the fiber content of SBP is also higher. SBP can avoid 25% emissions from beef production per kg of live animal weight.Sustainability 2018, 10, 4184 2 of 23 supported by the Portuguese Government through the Portuguese Carbon Fund (PCF), to assist the country in keeping with Portuguese goals for the Kyoto Protocol under the Agriculture, Forestry, and Other Land Uses activities of Article 3.4. The PCF supported the installation and maintenance of SBP using a system of service payments for carbon sequestration. As a consequence, 1095 farmers installed SBP in an area of more than 4% of the country's agricultural land [10]. The majority of the area of SBP (over 90%) was installed in the agricultural region of Alentejo; namely in highly important "Montado" areas, an agro-forestry landscape of high biodiversity value [15].The high yields of SBP are achieved because of (a) the biodiversity effect on productivity, (b) the selection of high-yield and locally adapted grass and legume species, and (c) technical support for precision management that often involves phosphate fertilization and pH correction using limestone [10]. To farmers, the costs with management are counter-weighed by a decrease or elimination of the need for commercial concentrate feeds for ruminants, because SBP increased productivity when compared with their most common alternative land use system observed in farms before sowing-semi-natural pastures (SNP). Savings in concentrate feeds are an additional ecological and economic benefit for the country [9].Despite the savings in feed consumption, SBP require more agricultural operations and inputs for production, such as seeds production and machinery for installation, and regular applications of phosphate fertilizer and limestone for maintenance. So far, a plot-level assessment of GHG emissions has been carried out [16], but no life cycle assessment (LCA) study has ever been carried out to also a...