Well, this is nice to know. I don't have that many chickens either, and usually have hay down, so it's the soiled hay that I put out on the garden. Between crops, we till it in, so there is time for it to break down. I've never worried much about salmonella. My chickens are healthy. I keep the water buckets, and feeders clean. During our rainy season, I discard any feed that clumps, is off color, or just doesn't look right to me, which minimizes the risk.