It happened around 5:30 a.m. at a construction zone south of Madisonville.
The driver of the semi, John Book, wasn't hurt, but 50 of the 100 cows being carried were killed.
Northbound traffic was closed at the construction site while southbound traffic was re-routed at the Morton's Gap exit.
Traffic started reopening just after 11 a.m., but backups are still possible at the site.
A semi has turned over on the Pennyrile in the median.
This happened around 5:30 am in the construction zone close to the Western Kentucky Parkway.
Our crew on scene tell us the semi turned when it dropped off the shoulder of the road.
The semi is on its side, affecting southbound traffic that is already down to one lane due to repairs.
Right now traffic is moving very slow..
The truck was carrying a dozens of cows and troopers tell us some of those cow have died.
Right now another truck is working to move the live cows out of the semi.
The driver was not hurt.
You should avoid this area for at least the next hour.