A 63-year-old man was also arrested at Peter Boddy Slaughterhouse in West Yorkshire, the other plant where operations were suspended on Tuesday in an investigation by the Food Standards Agency.
Dyfed-Powys Police has confirmed three people are being held on suspicion of offences under the Fraud Act.
They are being detained at Aberystwyth Police Station, where they will be interviewed jointly by the police and the FSA.
More top news
It'll be an unsettled afternoon across Wales, with blustery winds and heavy rain. Gales expected in many areas.
A bronze war memorial which was moved from a fire damaged chapel in Aberystwyth seven years ago is now being returned to its original place.
The compulsory 'scores on the doors' system is helping to drive up standards across Wales, according to the Deputy Health Minister.