Changes in the nutrient profile and the load of mycotoxins, phytoestrogens, and pesticides in horse pastures during spring and summer in Austria.
Authors: Son Viola, Penagos-Tabares Felipe, Hollmann Manfred, Khiaosa-Ard Ratchaneewan, Sulyok Michael, Krska Rudolf, Zebeli Qendrim
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Austrian researchers monitored seven horse pastures across spring and summer to establish how nutritional value and contaminant levels shifted with plant maturity and environmental stress, sampling at ear emergence, full bloom, and drought-damaged stages. The nutrient profile changed markedly with plant development and weather conditions: drought-stressed pastures showed increased fibre ratios alongside higher calcium, iron and magnesium but depleted potassium—a mineral balance shift with clear implications for metabolic stability and performance. Contaminant analysis revealed an extensive contamination landscape, with 64 fungal metabolites dominating (particularly Fusarium species reaching 123–3873 µg/kg dry matter), plus phytoestrogens, cyanogenic glycosides, bacterial metabolites and pesticides; critically, drought conditions substantially elevated mycotoxin loads across all pathogenic groups. These findings underline that grazing management cannot be divorced from seasonal and climatic factors: practitioners monitoring horses on pasture should anticipate seasonal shifts in micronutrient availability and recognise that drought-stressed swards pose genuine toxicological risk, warranting supplementation strategies, rotational grazing adjustments, or conserved forage replacement during vulnerable periods.
Read the full abstract on PubMed
Practical Takeaways
- •Monitor pasture conditions during drought periods, as stress significantly increases mycotoxin contamination—consider supplementing or rotating to alternative forage sources during dry summers.
- •Test pasture samples during critical growth stages (ear emergence through full bloom) to establish baseline contamination profiles and adjust grazing management accordingly.
- •Be aware that drought-stressed pastures may have altered mineral ratios (higher calcium, iron, magnesium; lower potassium), which could affect equine mineral balance and require dietary adjustments.
Key Findings
- •Drought-damaged pastures showed increased acid-to-neutral detergent fiber ratio with elevated calcium, iron, and magnesium but lower potassium contents.
- •Fusarium metabolites dominated fungal contaminants with concentrations ranging from 123–3,873 µg/kg DM, increasing significantly under drought-induced stress.
- •Pastures contained 64 fungal compounds including ergot alkaloids, metabolites from Fusarium, Aspergillus, Penicillium, and Alternaria species, plus phytoestrogens and cyanogenic glycosides.
- •Plant developmental stage, botanical composition, and weather conditions were dominant factors affecting both nutritional composition and contaminant presence in pastures.