AIDAN O’Brien and Coolmore Stud have initiated legal proceedings against feed company Glanbia over contaminated feed which led to the withdrawal of all O’Brien’s intended runners on Prix de l’Arc de Triomphe day in 2020.

According to a report in The Irish Times, O’Brien, his son Donnacha and eight Coolmore-associated companies are suing the parent company of Gain equine nutrition over losses incurred by the enforced non-participation of 11 horses at the prestigious meeting in Paris.

Aidan O’Brien withdrew four horses from the 2020 Prix de l’Arc de Triomphe at the last minute, and seven more from other races over the weekend, when pre-race tests carried out by French racing authorities confirmed traces of the prohibited substance zilpaterol in their system.

The Ballydoyle trainer was alerted to the possibility that his horses could test positive by the feed company following reports of a handful of positive tests returned by racehorses in France who had been exposed to the same batch of feed.

Zilpaterol is used as a feed supplement for cattle outside Europe. A contaminated shipment of molasses which came from South America is thought to have been the source of the zilpaterol in the horse feed.

Glanbia has already taken legal action against the molasses supplier, suing for €9 million.

Oddly, there were no positive tests for the substance returned by the laboratories testing Irish and British racehorses at that time, suggesting that the French laboratory’s testing regime was more sensitive.