Animal liveweight gain from lucerne and lucerne/grass mixes

Abstract

Animal production from lucerne has proved superior to other pastures in dryland situations, however there is interest in lucerne/grass mixes an as alternative to lucerne monocultures. A farmlet study was set up with lucerne monocultures, lucerne/cocksfoot and lucerne/brome mixes. Annual liveweight production was 865 kg/ha for lucerne monocultures and lucerne/cocksfoot, compared with 746 kg/ha for lucerne/brome. During spring, 78% of total liveweight production was from lambs that maintained growth rates of ∼300 g/head/d on all pastures. Accumulated dry matter yields were ∼12 t/ha for all pastures. All pastures used 612 mm of water at an efficiency of 22 kg DM/ha/mm. Temperature did not influence dry matter yield across pastures, all produced 5.5 kg DM/ha/°Cd. Botanical composition was similar for all pastures, but livestock on lucerne monocultures consumed 100 kg DM/ha more weeds than lucerne/grass. Stock grazing lucerne/brome actively selected for legumes, and against brome and dead material, resulting in a decline in pasture quality. Differences in liveweight gain were explained by different stocking rates for each treatment, not by quantity or quality of herbage. Utilizing a ‘leader follower’ system of ewes and lambs followed by cattle could aid to maintain the herbage quality of lucerne/grass mixes by avoiding a built up of reproductive and dead material.