Summary: The effects of feeding concentrates with alternative ingredients to cereal and soybean meal on growth performance, carcass characteristics and meat quality traits of feedlot lambs were studied. A total of 105 non-castrated male lambs were randomly assigned to one of three treatments (5 replicates per treatment): Control (CON, similar to commercial concentrates), Camelina (CAM, where camelina meal replaced 50% of the crude protein from the soybean meal in the CON concentrate), and Fibrous (FIB, concentrate without cereals and soybean meal, with camelina meal in addition to several by-products, and 20% less energy). The CAM treatment performed as well as the CON one. The FIB treatment increased feed conversion rate and tended to improve the redness and the oxidative stability. The CAM and FIB were economically more favourable. We found that a concentrate for feedlot lambs based on alternative ingredients, including several by-products, could be a feasible alternative to typical cereal-soybean meal-based concentrates.