Rónán Mullen (Independent) | Oireachtas source

I am trying to establish whether the case was where a substance was in an additive that went into feed that was supplied, and where the Department of Agriculture, Food and the Marine was interested.

It was established that it was in feed that went to horses, but only in certain stables. What was found? Was there wrongdoing in that case? Why was that substance in the feed?