Members of the police, fire and ambulance services arrived at the factory at about 9am, after reports of an unpleasant smell coming from the site on Blenheim Road.
The East Midlands Ambulance Service’s hazardous area response team attended the scene, as well as an air ambulance.
Paramedics treated 35 workers at the factory, while two patients were taken to Royal Derby Hospital with minor ailments by a non-emergency ambulance.
‘An unknown odour’
A Moy Park spokesman said: “As a precautionary measure we halted production in part of our Ashbourne facility for a short period while we investigated the cause of an unknown odour.
“In line with our procedures, staff were evacuated from the area and emergency services supported the site.”
Emergency services left the area at about 11:20am.
Meanwhile, Carlsberg UK has claimed the safety of its employees is of the “utmost importance”, after being served an improvement notice from the Health and Safety Executive following a gas leak that led to the death of one of its workers.