The pigs managed to break through a fence before meandering on the westbound carriageway between junctions 12 (Eccles Interchange) and 11 (Birchwood Interchange).
The motorway was blocked from around 10.15am to 11am while traffic officers worked to move the pigs back to their field.
A spokesman for National Highways said: "Traffic has been temporarily stopped due to a number of pigs which are being a bit of a swine and won't move."
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Motorists were warned to add an extra 45 minutes to their journeys as four miles of stationary traffic built on the carriageway.
Once the pigs were returned back to their field, officers reopened two out of three lanes while they secured the fence.
The motorway fully reopened at approximately 11.20am and congestion has eased in the area.
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