The replacement of marginal cereal crops in semi-arid, rainfed areas by a forage system keeping a stable stocking rate throughout the year was studied. The trial was conducted in an experimental farm of thirty-two ha, divided into four fenced plots dedicated to different crops: (i) alfalfa; (ii) winter cereal; (iii) Lolium rigidum plus annual medics; and (iv) Atriplex halimus shrubs. Crops were grazed rotationally by a flock of local ewes during the year. Natural mating took place in October. Ewes lambed outdoors and the lambs were kept permanently with their mothers until reaching a slaughtering weight of 22-25 kg. The forage system, based on the successive use of alfalfa, winter cereals and the shrub Atriplex halimus, made possible a stocking rate of two ewes per ha and a mean production of 1.2 lambs per ewe per year with only one lambing period in March.