Seed contamination in sheep: New investigations into an old problem

Seed contamination significantly reduces production capacity and welfare in Australian sheep flocks, leading to considerable losses to producers and processors across lamb and mutton value chains. Seven grass weed species are major contributors to seed contamination, with barley grass (Hordeum spp.) identified as a key perpetrator. Herbicide resistance and variable dormancy now emerging in southern Australian barley grass populations are likely to be augmenting invasion capability, further exacerbating the potential for seed contamination. This article reviews the current literature identifying the impact of seed contamination on sheep meat production. Data is presented on influencing incidence of carcass contamination with particular reference to key grass weed species prevalence across Australia and its congruence with weed invasion patterns. Key areas requiring future research are defined, including the development of integrated management options for significant weeds contributing to carcass damage, the assessment of management impacts on weed populations over time and the determination of economic thresholds for control in lamb production systems. Understanding the biology of key weeds, historical influences and economic consequences associated with seed contamination in sheep may assist in defining future risks to sheep production and improving weed management. Furthermore, examining more recent data describing the current status of seed contamination across Australia and the associations with causal weeds may also aid in the development of critical weed control strategies in regions showing high weed infestation rates, subsequently limiting the extent of future seed contamination in these areas.