Considering that you have ALL ENGINE performance from V1 - 400 feet, if the engine failed at that point, your climb gradient would decrease towards the 2.4% minimum gradient and slightly less if you then selected Anti-Ice.
The average gradient by the time that you reached 1500 feet MIGHT be 2.4%. But there are no guarantees!
If you need Anti Ice that badly, you should insist that your takeoff weights are calculated with ANTI-ICE ON.
Mutt