The driver lost control of the vehicle on the Gledrid island on the Shropshire side of the Welsh border at around 2.30am.
Long rush hour tail backs built up for traffic travelling north from the Oswestry direction. Traffic was diverted through the town of Chirk.
Following the crash a major rescue operation got underway to transfer the birds to another wagon. A diesel spillage also had to be dealt with.
Emergency services responded to the 999 calls following the crash, including four fire crews. No-one was hurt.
A Shropshire Fire and Rescue spokesman said: "At 2.37am on Thursday, July 21, SFRS Fire Control received a call reporting that a road traffic collision had taken place in Oswestry involving one lorry carrying poultry.
"Fire crews investigated area using thermal image camera and one environmental grab pack was used to protect storm drains from fuel spillage.
"Arrangements were made for transfer of stock to another vehicle. Shropshire Highways dealt with the clear up of fuel spillage, damage to road and road closure. Shropshire Fire Service handed the incident over to police.
"Four fire appliances including the rescue tender were mobilised from Oswestry and Wellington. An operations officer was in attendance."