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.

Animal and forage responses on lucerne (Medicago sativa L.) pastures under contrasting grazing managements in a temperate climate

“…For example, in a farm system, which cannot easily increase the stocking rate, the greater forage production of the T350 grazing strategy could be conserved to increase resilience. This situation is consistent with results from sheep grazing lucerne on‐farm in New Zealand (Anderson et al., 2014; Avery et al., 2008; Moot, Anderson, et al, 2019; Moot, Smith, et al, 2019). In both countries, changes in animal production were achieved through changes in grazing management to align crop growth and development with animal production (Moot et al., 2003).…”

“…These grazing recommendations have been implemented on farms in New Zealand and transformed animal production systems. However, the animal production data are based on sheep (Anderson, Anderson, Moot, & Ogle, 2014; Avery, Avery, Ogle, Wills, & Moot, 2008; Moot, Anderson, Anderson, & Anderson, 2019; Moot, Smith, & Mills, 2019). It remains to be seen whether these general recommendations hold for other animal production systems in different parts of the world.…”

Animal performance changes over 11 years after implementing a lucerne grazing system on Bog Roy Station

“…Across the time period, there have been many management changes, but integral to all of them has been to understand the legume management required to drive animal production. Anderson et al (2014) outlined the traditional highcountry management reflected for fine wool production in 2008. The bulk of the hill country was set stocked for lambing after a minimal period of spelling and therefore little time for pasture recovery.…”

“…In the period 2009-2011, there was a step change in lamb production to ~111 t of weaned lamb, from a similar number of ewes compared with 91 t in 2008 ( Figure 1). This increase was associated with greater grazing of the lucerne during the lactation period (Anderson et al 2014). Paddocks of lucerne (~12 ha) that had previously been used for conservation, were split into six smaller paddocks with electric fences and rotational grazed with merino ewes and lambs, following strict management rules (Moot et al 2003).…”

“…In 2008, the owners of Bog Roy Station (in the Upper Waitaki region) sought advice on how to adapt a lucerne grazing system to their extensive high-country farm. Their rationale for the change and the operational requirements undertaken were detailed by Anderson et al (2014). These management changes have led to significant improvements in animal performance across the merino flock.…”