We think we have been struck by cocklebur toxicosis.
In the past month, we have lost 5 healthy cows to poisoning from... cocklebur seedhead maybe, we believe. But we don't know. It is very confusing. We have had cocklebur on the farm indefinitely, but never to this extent. Eighty inches of rain last year, followed by a very wet winter, while cattle moved across the landscape, created conditions for explosion of this annual forb this summer. Cattle on wet pastures create mud, and open ground attracts annual weeds, like cocklebur. The seedhead is toxic, but not the leaf. Cattle and sheep like the leaf, but avoid the prickly seed. Perhaps the odd bovine, however, ingests the seedhead by accident, and then suffers fatal consequences. But why only 5% of the herd and why only mature, seasoned cows who should know better? Leaves of wild cherry trees are toxic, when first cut. Stinging Nettle, Milkweed, and nightshades can also be poisonous, all of which proliferate in pastures.
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