Hay is often bound up into bales with plastic twine. Cattle happily eat bits on accident. They used to use wire, but that caused a much more serious problem for the cattle.

I visited the largest pig farm in Ohio and they grind up bags of old dog food, plastic bags and everything. Literally pallets full of expired food, just dumped into the grinder. Then they spread the waste and sell it as organic fertilizer, plastic is now everything.