This study investigated various pasture management strategies employed to avoid hypoglycin A (HGA) intoxication in horses.

Sycamore seedlings from nine locations were either mowed (n = 6) or sprayed with a herbicide (dimethylamine‐based n = 2; picolinic acid‐based n = 1). Seedlings were analyzed for HGA concentration before intervention and at 48 hours, 1 and 2 weeks after. Cut grass in the vicinity of mowed seedlings was also analyzed prior to and 1 week after intervention. Seeds and seedlings maintained for 6 months in processed grass forage (hay and silage) were also analyzed.

There was no significant decline in HGA content in mowed or sprayed seedlings; with mowing inducing a temporary significant rise in HGA in the seedlings. HGA was still present in sycamore material after 6–8 months storage within either hay or silage.

Bottom line: Neither mowing nor herbicidal spraying reduces HGA concentration in sycamore seedlings up to 2 weeks after intervention. Pastures contaminated with sycamore material should not be used to produce processed hay or silage.

This article, “Atypical myopathy‐associated hypoglycin A toxin remains in sycamore seedlings despite mowing, herbicidal spraying or storage in hay and silage,” was authored by González‐Medina, S.; Montesso, F.; Chang, Y.‐M.; Hyde, C.; and Piercy, R.J.

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