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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In the last of the current series of Face to Face, Adrian Masters talks to the journalist and author Nesta Wyn Ellis
A wet and blustery start to the day, but it will brighten up this afternoon!
Well I can promise it's not the nicest of nights out there! Turning wet with heavy downpours in places.