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.
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The heavy showers will ease during the first part of tonight, leaving a dry night with mist in places.
A 1950s pin-up girl from the Vale of Glamorgan has returned to the spot where she won the nation's hearts.
The band play the Liberty Stadium on Saturday night as part of their 'Everything Must Go' 20th anniversary tour.