Pasture Management to Reduce the Risk of Acer pseudoplatanus Poisoning While Preserving Ecological Sustainability

In spring, grazing equids may suffer from a severe rhabdomyolysis syndrome named atypical myopathy. This environmental intoxication results from ingestion of toxins contained in Acer pseudoplatanus seedlings. The aim of this study was to investigate the effectiveness of herbicide spraying and mowing to reduce the toxic pressure of sycamore seedlings. In a first experiment, the efficacy of three herbicides to eradicate seedlings was compared to mowing. In a second experiment, the influence of the mowing timing on pasture productivity was determined. In both experiments, sycamore seedling counting, grass height and botanical composition were determined. In experiment 2, the final harvest biomass and its nutritional value were also determined. Herbicides and mowing both reduced the number of seedlings, which nevertheless disappear naturally over time without intervention (i.e., in control areas). As opposed to mowing, herbicide spraying altered the composition of the pasture flora. Both sprayed and mowed seedlings remain toxic until full decomposition. Early mowing (i.e., early April) did not affect the harvest yield. Late mowing (i.e., end of April) reduced the harvest yield but its nutritional value fitted the horses’ need. In conclusion, mowing is the best strategy to reduce the risk of Acer pseudoplatanus poisoning in grazing equids while preserving ecological sustainability and nutritional value of pastures.