Integrating lucerne (Medicago sativa L.) into a high country merino system

Abstract

Farm systems in the dry sub-humid region of the Upper Waitaki predominantly graze merino ewes on extensive oversown and topdressed hill and high country. Smaller areas of flatter land are used to conserve winter forage crops, and grow supplementary feed and high quality pastures. The slow growth rate of merino lambs means they are traditionally retained on these improved pastures to finish in the following spring. In this system livestock demand peaks in the driest month of January and continues to be high through winter. Bog Roy is a farm that has changed this system and has established 200 ha of lucerne with the goal of fully feeding ewes during lactation. Pre-weaning lamb growth rate has increased from 205 to 235 g/head/day, opening the opportunity to sell heavier lambs in early January. Ewe lamb replacements are reaching heavier pre-winter live weights (38 kg versus 35 kg) and the flow-on effect is higher two-tooth scanning (129% versus 111%) and weaning (100% versus 84%). Lucerne has also improved the feeding of mixed age ewes from lambing to weaning, and lamb mortality has reduced from 30% to 21%, increasing weaning from 115% to 130%. The store production system also means livestock demand is kept low during the dry period and remains low through winter. Conserved feed is now only required for 50 days compared with 100 days in the traditional system. This has reduced supplementary feed costs from $10.33/stock unit (SU) to $4.82/SU. Shifting ewes to rotationally graze lucerne in large mobs early in the growing season has decreased the stocking rate on hill country. This has allowed cover to build during each spring with promising responses from legume species.