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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Investigating officers say a driver's intentions were "genuine" when he offered a mother and child a lift during a downpour.
The Wales squad have been put through their paces ahead of tomorrow's Six Nations clash against Scotland in Cardiff.