Animal performance over 16 years after implementing a lucerne grazing system on Bog Roy Station – A case study

Abstract

This case study reports the impact on animal performance from changes in the feed supply on Bog Roy Station measured over 16 years. Since 2008, feed supply has been increased through expansion of the dryland lucerne area and use of legume dominant grass mixes under irrigation. In 2023, 154 t weaned lamb liveweight was produced from 4272 Merino ewes plus 9.0 t from hoggets. Mixed age ewes are now consistently 65.6±1.17 kg/hd at mating (2019-2023) and two-tooth weight at mating has increased 0.74±0.14 kg/ hd/yr (R² = 0.64) from 52 kg/hd in 2012 to 61 kg/hd in 2023. Pregnancy scanning is now ∼167±1.59% for the mixed age ewes (2012-2023) and has increased from 113% (2008) to 154% (2023) in the two-tooths. Lamb wastage (scanning to tailing) for the mixed age ewes has decreased 0.70±0.08%/yr (R² = 0.88) from 24% (2012) to 15% in 2023. The wastage in two-tooths has reduced from 32% (2014) to 21% (2023). Lamb wastage was negatively related to two-tooth weight at set-stocking, so feeding light young stock is a priority. Since 2016, pre-weaning lamb growth rates have averaged 286±4.39 g/hd/d and weaning now occurs at 79.3±2.56 days, or 40 days earlier than in 2008. The consistency in pre-weaning lamb growth rates has coincided with the development of 210 ha of pivot irrigation which now grow lucerne/grass mixes. The increased animal production has not affected wool production and cow numbers have increased to cope with surplus pasture on hills. The major change in farm income has resulted from the earlier sale of more and heavier prime lambs at a higher average price associated with the extra feed available to ewes during lactation, and weaned lambs. This unique long-term dataset of on-farm performance provides a commercial example of transformational change in the farm system driven by an increased area of lucerne grazed by ewes and lambs during lactation. Subsequent, irrigation development has been focused on growing young stock to prime weights which is now allowing a proportion of hoggets to be mated.