Question about cow manure...

Sorry, I know that is a less than lovely subject, but my husband brought some cannabis home last night. A friend's brother-in-law had grown it outdoors. He said he grew it in pure cow manure...I didn't think that was possible. He just started the seedlings and put them in the pile behind the barn. The thing is, it was great! I haven't had such an up high for a long time, a total motivational experience. I'm assuming it was a sativa strain...but pure cow manure? Is he telling the truth?:D