Abstract
Ecological studies on the recently described nocardioform actinomycete Rhodococcus coprophilus have shown that very high numbers of this organism can be isolated from the dung of domesticated herbivores and that growth occurs in this substrate. The coccal survival stage contaminates grass in pastures or hay used during the winter months for fodder, and remains viable after ingestion and passage through the rumen. The excreted organism is washed into streams and rivers and can be isolated in high numbers from stream sediments and lake muds. The ratio of R. coprophilus to other actinomycetes in stream water samples should provide a useful index for detecting the presence of dairy farm effluents.