Maybe not the best overall, but definitely the cheapest and easiest thing a consumer can do, right now, today, is eat less red meat.

There are already subsidies which incentivize the production of cattle. Just like with corn, if demand goes down, they'll just find a way to use cattle for something else (like turning it into feed or some energy source). The average citizen has very say in macro-economic supply chains.

I highly doubt ranchers would turn to grinding up beef herds just to make more feed. They would just grow more forage/feed crops. But they really wouldn't since it's the beef that needs the absurd volume of feed, so ideally they would just go out of business.