Forage brassicas can enhance the feed base and mitigate feed gaps across diverse environments

Context Spring-sown forage brassicas are commonly used to fill feed gaps in high-rainfall temperate livestock systems, but they have wider potential as an autumn-sown forage in drier environments within Australia's crop-livestock zone.Aims We modelled the production potential of autumn-sown forage brassicas grown in diverse environments and tested their ability to alter the frequency and magnitude of feed gaps.Methods Long-term production potential was simulated in APSIM for four forage brassica genotypes, compared with forage wheat and dual-purpose canola across 22 diverse agro-climatic locations. For seven regions, the change in frequency and magnitude of forage deficits from adding forage brassicas to representative forage-livestock systems was predicted.Key results Across locations, median yields of forage brassicas ranged from 7 to 19 t DM/ha, and their annual metabolisable-energy yield was higher than that of forage wheat at most sites and nearly always exceeded dual-purpose canola. Forage brassicas performed better than forage wheat in later-sowing events (late April to early May) and maintained growth and quality later into spring. At five of the seven regions, adding 15% of farm forage area to forage brassicas reduced the frequency and magnitude of feed deficits by 35-50% and 20-40%, respectively. However, they were less beneficial where winter-spring feed gaps are uncommon.Conclusions We demonstrated that autumn-sown forage brassicas can be reliable and productive contributors to the feed base in drier environments and are a suitable alternative to forage cereals.Implications Forage brassicas can help reduce feed gaps and improve livestock production in a range of production systems spanning Australia's crop-livestock zone. Long-term simulation modelling showed that autumn-sown forage brassicas can serve as a reliable and valuable forage source in drier environments across Australia's crop-livestock zone. They have a long grazing window and stable production across a range of sowing dates and environments. Integrating forage brassicas into the existing feed base can reduce the frequency and magnitude of on-farm feed deficits in livestock production systems. They can also allow for a safe increase in stocking rates and reduce the need for supplementary feed.