FDR did stuff like this (killing cows, destroying crops, etc.) to keep the prices high on farm goods. Higher prices meant more profit to the farmers! (I’m guessing that you had to be the right kind of farmer).
A farmer also was jailed(?), fined(?) or both(?!) for feeding his own hay to his own cows. It was a violation of the Interstate Trade Agreement (or something).
He was supposed to have destroyed that hay. And it was in violation of the ITA because if he had destroyed it, then he would have bought hay from someone else, who may have been from another state.
That story comes up when folks on FR try to explain why so many rules become enacted. I think it comes up in the Obamacare discussions, and I think with the new rules on organic farming and home gardens.
I probably messed up some of the details, but that is the gist of things IIRC.
This is the case about the wheat farmer, the Agricultural Adjustment Act of 1938 and the federal government’s authority to regulate production not intended in any part for commerce, but wholly for consumption on the farm: Wickard v. Filburn - 317 U.S. 111 (1942)
http://supreme.justia.com/cases/federal/us/317/111/case.html