Performance of lambs grazing an annual Mediterranean pasture or fed supplements based on olive oil cake or maize and its influence on system outputs

Abstract

Three lamb feeding strategies were compared, including finishing of suckling lambs on an annual Mediterranean pasture (GRAZE), weaned followed by a concentrate plus hay diet (CONC), or weaned and fed a concentrate with 33% dry olive oil cake plus hay (CAKE). Grazing lambs averaged a liveweight gain of 334 g/day during the 28-day experimental period, which was higher (P < 0.05) than that of CONC and CAKE (283 and 276 g/day, respectively); however, there were no differences in empty body or dressed carcasses weights due to dietary treatment. The feed conversion of the olive seed cake supplement (kg supplement/kg gain) was lower (P < 0.01) than that of the maize-based supplement. Despite some significant differences between carcasses traits, all were small and of little commercial consequence. Simulation modelling of whole-system performance suggested that early weaning of lambs followed by concentrate feeding would reduce the finishing period, marginally increase the liveweight of ewes and would have little effect on pasture availability. It was further concluded that olive oil cake can be a large proportion of concentrate diets without negatively affecting carcass quality.